&EPA
EPA/600/R-12/577 | December 2012 | www.epa.gov/ord
United States
Environmental Protection
Agency
Protocol for Detection of
Bacillus anthracis in
Environmental Samples
During the Remediation Phase
of an Anthrax Event
Office of Research and Development
National Homeland Security Research Center
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Detection of Bacillus anthracis in Environmental Samples
f/EPA
United States Environmental Protection Agency
National Homeland Security Research Center (NHSRC)
Threat and Consequence Assessment Division
26 West Martin Luther King Dr.
Cincinnati, OH 45268
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Detection of Bacillus anthracis in Environmental Samples
Table of Contents
Disclaimer iii
Foreword iv
Trademarked Products vii
Acknowledgements viii
Introduction 1
1.0 Scope and Application 4
2.0 Summary of Methods 4
3.0 Interferences and Contamination 5
4.0 Safety 5
4.1 Laboratory Hazards 5
4.2 Recommended Precautions 5
5.0 Supplies and Equipment 7
5.1 General Laboratory Supplies 7
5.2 Supplies for RV-PCR Analysis 8
5.3 Supplies for Real-time PCR Analysis 8
5.4 Supplies for Culture 9
5.5 Equipment 9
6.0 Reagents and Standards 10
7.0 Calibration and Standardization 14
8.0 Quality Control (QC) 15
9.0 Site Characterization Procedures 17
9.1 Sample Processing for Laboratories With RV-PCR Capability 17
9.2 DNA Extraction and Purification 21
9.3 Real-time PCR Analyses 22
10.0 Post Decontamination Procedures for Rapid Viability-Polymerase Chain Reaction (RV-PCR)
Analyses 26
10.1 RV-PCR 26
10.2 RV-PCR Sample Processing: Spore Recovery 29
10.3 RV-PCR Sample Processing: Buffer Washes and Broth Culture 33
10.4 Manual DNA Extraction and Purification 35
10.5 Real-time PCR Analysis of To and T9 DNA Extracts 38
11.0 Post Decontamination Procedures for Culture Analyses 39
11.1 Sample Processing and Plating for Sponge-Sticks and Wipes 40
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Detection of Bacillus anthracis in Environmental Samples
11.2 Sample Processing and Plating for Swabs 42
11.3 Sample Processing and Plating for Air Filters 44
11.4 Sample Processing and Plating for Vacuum Socks and Filters 46
11.5 Sample Processing and Plating for Water Samples 50
11.6 Confirmation of B. anthracis Colonies by Real-time PCR Analysis 52
12.0 Data Analysis and Calculations 53
12.1 Real-time PCR During the Site Characterization Phase 53
12.2 RV-PCR 54
12.3 Culture 54
13.0 Method Performance 56
14.0 Pollution Prevention 56
15.0 Waste Management 56
16.0 References 56
Appendix A
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Detection of Bacillus anthracis in Environmental Samples
Disclaimer
This document has been reviewed in accordance with U.S. Environmental Protection Agency (EPA)
policy and approved for publication. Note that approval does not signify that the contents necessarily
reflect the views of the Agency. Mention of trade names, products, or services does not convey EPA
approval, endorsement, or recommendation.
Questions concerning this document or its application should be addressed to:
SanjivR. Shah, Ph.D.
National Homeland Security Research Center (NHSRC)
U.S. Environmental Protection Agency
1300 Pennsylvania Avenue, NW
USEPA-8801RR
Washington, DC 20460
(202) 564-9522
shah.sanj iv@epa.gov
If you have difficulty accessing this PDF document, please contact Kathy Nickel
(Nickel.Kathy@epa.gov) or Amelia McCall (McCall.Amelia@epa.gov) for assistance.
/'/'/' December 2012
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Detection of Bacillus anthracis in Environmental Samples
Foreword
Following the 2001 terrorist attacks and the anthrax bioterrorism event, several Presidential Directives
broadened the U.S. Environmental Protection Agency's (EPA's) mission to include key aspects of
homeland security. EPA was directed to protect human health and the environment from harmful effects
of chemical, biological and radiological contamination. To effectively respond to such events, EPA
established the Environmental Response Laboratory Network (ERLN) and Water Laboratory Alliance
(WLA), the laboratory network responsible for analyses of environmental and water samples. In the
event of the release of a bioterrorism agent such as Bacillus anthracis (B. anthracis), hundreds to
thousands of environmental samples will need to be processed and analyzed in a timely manner to support
decontamination planning efforts. Analytical results, in addition to technical expertise, will be provided
to those responsible for making clearance decisions. To address these critical needs, EPA's National
Homeland Security Research Center (NHSRC), in collaboration with the Centers for Disease Control and
Prevention (CDC) and Lawrence Livermore National Laboratory (LLNL), has developed this protocol for
detection of B. anthracis in environmental samples, including drinking water.
The "Protocol for Detection of Bacillus anthracis in Environmental Samples During the Remediation
Phase of an Anthrax Event" includes response-phase-appropriate sample processing and analytical
procedures for determining the presence or absence of B. anthracis spores in a cost-effective and time-
efficient manner. This protocol includes sample processing procedures appropriate for the real-time
polymerase chain reaction (PCR) analytical technique used during the site characterization phase. Since
determination of whether viable B. anthracis spores are present in the samples will be required during the
post decontamination phase of the response, sample processing methods appropriate for traditional
microbiological culture and EPA's Rapid Viability (RV)-PCR analytical procedures are also included.
Although Laboratory Response Network (LRN) laboratories will provide analytical support to EPA by
analyzing environmental samples, they will be using LRN-specific protocols as opposed to this protocol.
NHSRC has made this protocol available to ERLN and WLA labs for the analysis of samples to assist in
preparing for and recovering from disasters involving contamination from B. anthracis spores. This
milestone specifically represents a strong and continuous commitment of NHSRC's research in support of
the ERLN and WLA. It also exhibits EPA's commitment to fulfill its homeland security mission and its
overall mission to protect human health and the environment.
Jonathan Herrmann, Director
National Homeland Security Research Center
Office of Research and Development
U.S. Environmental Protection Agency
December 2012
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Detection of Bacillus anthracis in Environmental Samples
List of Tables
Table 1. Sample Processing Negative Controls 16
Table 2. Example EPA-2 PCR Assay Master Mix Preparation for 70 Reactions 24
Table 3. Example EPA-1 and BC3 PCR Assay Master Mix Preparation for 70 Reactions 25
List of Figures
Figure 1. PCR Amplification 23
Figure 2. Example PCR Amplification Curves for the Initial T0 Aliquot and the Endpoint Aliquot 27
Figure 3. Flow Chart for RV-PCR Sample Analysis 28
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Detection of Bacillus anthracis in Environmental Samples
Acronyms
ABI Applied Biosystems®
BD Becton, Dickinson and Company
BHI Brain heart infusion
BMBL Biosafety in Microbiological and Biomedical Laboratories
BSC Biological safety cabinet
BSL Biological safety level
CBR Chemical, biological, radiological
CDC Centers for Disease Control and Prevention
CFR Code of Federal Regulations
CT Cycle threshold
DI Deionized
DNA Deoxyribonucleic acid
DQO Data quality objectives
EDTA Ethylenediaminetetraacetic acid
EIC External inhibition control
EPA United States Environmental Protection Agency
ERLN Environmental Response Laboratory Network
FEM Forum on Environmental Measurement
ICLN Integrated Consortium of Laboratory Networks
IEC International Electrotechnical Commission
ISO International Organization for Standardization
LLNL Lawrence Livermore National Laboratory
LRN Laboratory Response Network
MPN Most probable number
MSDS Material safety data sheets
NHSRC National Homeland Security Research Center
NIST National Institute of Standards and Technology
NTC No template controls
OSHA Occupational Safety and Health Administration
PAPR Powered air purifying respirator
PBST Phosphate buffered saline with Tween® 20
PC Positive control
PCR Polymerase chain reaction
PES Polyethersulfone
PMP Paramagnetic particle
PNC [Sample] processing negative control (Blank)
PPE Personal protective equipment
psi Pounds per square inch
PT Proficiency testing
QA Quality assurance
QC Quality control
RNA Ribonucleic acid
rpm Revolutions per minute
RV-PCR Rapid Viability-polymerase chain reaction
SBA Sheep blood agar
SOP Standard operating procedure
TO Time zero (no incubation)
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Detection of Bacillus anthracis in Environmental Samples
T9
TE
TNTC
UV
WLA
Nine hour incubation
Tris(hydroxymethyl)aminomethane-HCL-EDTA
Too numerous to count
Ultraviolet
Water Laboratory Alliance
Trademarked Products
Trademark
Acrovent™
BD Clay Adams™ Nutator Mixer
Biopur® Safelock®
Applied Bio Systems®
Autocup™
BBL™
Black Hole Quencher®
Costar®
Cole Farmer®
Dispatch®
Dynamag™
Fluoropore™
GN-6 Metricel®
Invitrogen®
Jiffy-Jack®
Kendall™
Life Technologies™
MagneSil® Blood Genomic
Masterflex®
MaxQ™
MicroFunnel™
Microcon®
Nalgene®
Stomacher®
TaqMan®
Trypticase™ soy agar
Tween®
Vacushield™
Versalon™
Whatman™
Holder
Pall Corporation
BD Diagnostics
Eppendorf
Life Technologies™
Whatman™ Ltd.
BD Diagnostics
Biosearch Technologies, Inc.
Corning
Cole Farmer®
Clorox Company
Life Technologies™
EMD Millipore
Pall Corporation
Life Technologies™
Cole Farmer®
Covidien, Inc.
Life Technologies™
Promega
Cole Farmer®
Thermo Scientific Inc
Pall Corporation
EMD Millipore
Nalge Nunc Corporation
Seward
Life Technologies™
BD Diagnostics
Sigma-Aldrich
Pall Corporation
Covidien, Inc.
Whatman™ Ltd.
Location
Ann Arbor, MI
Sparks, MD
United States
Carlsbad, CA
Maidstone, United Kingdom
Sparks, MD
Novato, CA
Tewksbury, MA
Vernon Hills, IL
United States
Carlsbad, CA
Billerica, MA
Ann Arbor, MI
Carlsbad, CA
Vernon Hills, IL
Mansfield, MA
Carlsbad, CA
Madison, WI
Vernon Hills, IL
Lenexa, KS
Ann Arbor, MI
Billerica, MA
Rochester, NY
United Kingdom
Carlsbad, CA
Sparks, MD
St. Louis, MO
Ann Arbor, MI
Mansfield, MA
Piscataway, NJ
December 2012
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Detection of Bacillus anthracis in Environmental Samples
Acknowledgements
This protocol was prepared under the leadership and direction of Sanjiv Shah of the National Homeland
Security Research Center within the U.S. Environmental Protection Agency's Office of Research and
Development.
The contributions of the following organizations and persons to this protocol are gratefully
acknowledged:
Centers for Disease Control and Prevention (CDC) - Laboratory Response Network (LRN)
• Richard Kellogg and Stephen Morse for their support and cooperation in the preparation and review of
this protocol
• Laura Jevitt for providing the LRN protocols that were adapted for inclusion in the protocol
Lawrence Livermore National Laboratory (LLNL)
• Staci Kane for her technical contribution and critical review of the protocol
U. S. Environmental Protection Agency (EPA) National Homeland Security Research Center
(NHSRC)
• Erin Silvestri, Tonya Nichols and Hiba Ernst for the overall support and review of the protocol
• Eletha Brady-Roberts and Ramona Sherman for the QA review of the protocol
EPA Office of Emergency Management (OEM)
• Marissa Mullins for the overall support and review of the protocol
Computer Sciences Corporation (CSC)
• Yildiz Chambers and Emily King for support in development and review of the protocol
• Rashmi Ghei for review of the protocol
Technical Reviewers
• Laura Rose and Vincent Hill (CDC)
• Sonia Letant (LLNL)
• James Anthony (Department of Homeland Security)
• Douglas Anders (Federal Bureau of Investigation)
• Stephanie Harris (EPA Region 10)
• Jafirul Hasan (EPA Office of Pesticides Program Microbiology Laboratory)
• Frank Schaefer, Gene Rice, Worth Calfee and Vincent Gallardo (EPA NHSRC)
December 2012
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Detection of Bacillus anthracis in Environmental Samples
Introduction
The series of 2001 terrorist attacks and the anthrax bioterrorism incidents that resulted in human
casualties, and public and private facility closures, prompted enhanced and expanded national safeguards.
Multiple Presidential Directives have designated the U.S. Environmental Protection Agency (EPA) as the
primary federal agency responsible for the protection and decontamination of indoor/outdoor structures
and water infrastructure vulnerable to chemical, biological and radiological (CBR) terrorist attacks.
EPA's mission, to protect human health and the environment, was thereby expanded to address critical
homeland security related needs.
The National Homeland Security Research Center (NHSRC) within the Office of Research and
Development is EPA's hub for providing expertise on CBR agents and for conducting research to meet
EPA's homeland security mission needs. A focus of NHSRC's research is to support the EPA's
Environmental Response Laboratory Network (ERLN), a nationwide network of federal, state, local and
commercial environmental laboratories which includes the Water Laboratory Alliance (WLA). Along
with the Centers for Disease Control and Prevention's (CDC's) Laboratory Response Network (LRN), the
ERLN can be activated in response to a large-scale environmental disaster to provide analytical
capability, increased capacity and produce quality data in a systematic and coordinated manner.
Preparedness against potential indoor or outdoor wide-area anthrax attacks is currently the highest priority
for the ERLN. Based on the realities of response activities after the 2001 anthrax event and continued
preparedness efforts since then, it is anticipated that in the event of an intentional (bioterrorist attack) or
accidental release of Bacillus anthracis (B. anthracis) spores, hundreds to thousands of diverse
environmental sample (e.g., aerosols, particulates and drinking water) will need to be rapidly processed
and analyzed in order to assess the extent of contamination and support the planning of decontamination
efforts. A similar number of samples will also need to be analyzed to determine the efficacy of
decontamination activities during the remediation phase of the response. During an anthrax event, EPA's
decision makers will need timely results from rapid sample analyses for planning the decontamination
efforts. To address these critical needs, NHSRC, in collaboration with CDC and Lawrence Livermore
National Laboratory (LLNL), has generated this protocol for detection of B. anthracis in environmental
samples.
To complement an effective sample collection strategy during an anthrax event, a systematic approach for
timely and cost-effective sample analyses is critical. Such a systematic approach also helps in effectively
managing and increasing the analytical laboratory capacity. This protocol attempts to present such an
approach for the detection of B. anthracis spores in various environmental samples (e.g., aerosol,
particulate [surface swabs, wipes, vacuum socks and filters, and Sponge-Sticks], drinking water). During
the remediation phase, prior to decontamination activities, EPA has to quickly determine the extent of
contamination in an affected building, facility, area or water system. Thus, for sample analyses during the
site characterization phase, detecting presence or absence of the deoxyribonucleic acid (DNA) of B.
anthracis by real-time polymerase chain reaction (PCR) is usually the most appropriate, and both time-
and cost-effective technique. Since determination of whether viable B. anthracis spores are present in the
samples will be required during the post decontamination phase of the response, either traditional
microbiological culture or EPA's Rapid Viability-PCR (RV-PCR) analytical procedures must be used.
Accordingly, the protocol presented here includes response-phase-appropriate sample processing and
analytical procedures. It should be noted that LRN laboratories will support EPA environmental sample
analyses during remediation using LRN-specific protocols.
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Detection of Bacillus anthracis in Environmental Samples
Sample processing procedures are provided for real-time PCR analyses conducted during the site
characterization phase. In addition, sample processing procedures appropriate for RV-PCR and culture
methods (for the post decontamination phase) are included. For drinking water samples, large volume
samples may need to be analyzed to detect low concentrations of B. anthracis spores or vegetative cells.
Therefore, the protocol also includes an ultrafiltration-based concentration procedure. For the post
decontamination phase culture analyses, selected isolated colonies will be analyzed using real-time PCR
to confirm the identity of B. anthracis as opposed to traditional biochemical and serological testing.
Many sample processing and analysis procedures in this document have been derived from LRN
protocols. However, these procedures have been modified, as necessary, to address EPA's homeland
security mission needs during the remediation phase of an anthrax event. Therefore, these modified
procedures or this protocol itself must not be designated, referred to, or misconstrued as LRN procedures
or protocol.
Since this protocol was developed to include the analyses of diverse environmental samples, it
emphasizes appropriate sample processing as well as the DNA extraction and purification steps to
significantly remove any growth- and/or PCR-inhibitory materials present in the samples. This protocol
will be revised as better sample processing procedures and real-time PCR assays become available.
It should be noted that as of the publication date of this protocol has not been validated. During any
B. anthracis related emergency situations, EPA's use of non-validated methods in the absence of
validated methods must adhere to the EPA's Forum on Environmental Measurement (FEM) policy
directive on method validation:
According to Agency Policy Directive FEM-2010-01, Ensuring the Validity of Agency Methods
Validation and Peer Review Guidelines: Methods of Analysis Developed for Emergency Response
Situations:
It is EPA's policy that all methods of analysis (e.g., chemical, radiochemical,
microbiological) must be validated and peer reviewed prior to issuance as Agency
methods. There are emergency response situations that require methods to be developed
and utilized, which may or may not have previously been validated or peer reviewed
prior to use. This policy directive addresses those situations in which a method must be
developed, validated and/or peer reviewed expeditiously for utilization in an emergency
response situation. Also, in such emergency response situations only, an analytical
method may be employed that has been validated by another established laboratory
network (e.g., the Center for Disease Control and Prevention's Laboratory Response
Network, the U.S. Department of Agriculture/Food and Drug Administration's Food
Emergency Response Network). In those instances, the responsible federal agency will
indicate that the level of validation and/or peer review that their analytical method
underwent is consistent with the Integrated Consortium of Laboratory Networks (ICLN)
5
Guidelines for Comparison of Validation Levels between Networks. The responsible
federal agency may also refer to the Validation Guidelines for Laboratories Performing
6
Forensic Analysis of Chemical Terrorism in order for the receiving federal agency to
determine if the analytical method meets the intended purpose.
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Detection of Bacillus anthracis in Environmental Samples
Any EPA regional or program office that proposes to utilize a method in an emergency
response situation is responsible for establishing and documenting to what level and by
what process the method has been validated and/or peer reviewed in accordance with this
policy. A regional or program office may determine the level of validation and/or peer
review that is necessary to provide the objective evidence that a method is suitable for its
intended purpose; however, the office must document the validation and/or peer review
information supporting use of the method. All documentation should be preserved in
accordance with the Agency's records management policy.
5
U.S. Department of Homeland Security, Integrated Consortium of Laboratory Networks (ICLN),
ICLN Guidelines for Comparison of Validation Levels between Networks, Original Version,
http ://www. icln. org/docs/sop.pdf.
6
Federal Bureau of Investigation (FBI), Scientific Working Group on Forensic Analysis of
Chemical Terrorism (SWGFACT), Validation Guidelines for Laboratories Performing Forensic
Analysis of Chemical Terrorism, Forensic Science Communications, Volume 7, Number 2, April
2005.
The above policy is available at:
http://www.epa.gov/fem/pdfs/FEM Policv2010-
01 Emergency Response Methods Final July 2010.pdf
Also, EPA recognizes that having analytical data of known and documented quality is critical in making
proper decisions during all phases of a response to an anthrax event and strives to establish data quality
objectives (DQOs) for each response activity. : These DQOs are based upon needs for both quality and
response time. EPA's ERLN, which is tasked with providing laboratory support following homeland
security-related events, also has established data reporting procedures. Requirements for receiving,
tracking, storing, preparing, analyzing and reporting data are specified in the Environmental Response
Laboratory Network Laboratory Requirements Document at:
http://epa.gov/erln/techsupport.html; project-specific requirements also are included in individual
Analytical Service Requests.
1 Information regarding EPA's DQO process, considerations and planning is available at:
http://www.epa.gov/QUALITY/dqos.html
December 2012
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Detection of Bacillus anthracis in Environmental Samples
Protocol for Detection of Bacillus anthracis in Environmental
Samples During the Remediation Phase of an Anthrax Event
December 2012
1.0 Scope and Application
The purpose of this protocol is to detect Bacillus anthracis (B. anthracis) spores in environmental
samples using real-time polymerase chain reaction (PCR) during the site characterization phase and to
detect viable B. anthracis spores using either Rapid Viability-PCR (RV-PCR) or culture followed by
isolate confirmation by real-time PCR during the post decontamination phase of the response. The real-
time PCR assays included in this protocol have been only partially characterized for specificity, however,
the use of these assays is currently recommended. These assays will be replaced with fully characterized
and validated assays upon availability. This protocol is intended for the analyses of swabs, wipes,
Sponge-Sticks, vacuum socks and filters, air filters, drinking water and decontamination waste water for
B. anthracis spores.
2.0 Summary of Methods
2.1 Site Characterization Phase - Sample Analysis for Detection (Real-time PCR): After samples
have been appropriately processed, the deoxyribonucleic acid (DNA) is extracted and purified.
DNA extracts are analyzed by real-time PCR using the Applied Biosystems® (ABI) 7500 Fast
Real-Time PCR System thermocycler. Direct DNA-based analysis of samples allows for high
throughput and rapid results. Unless advised otherwise, real-time PCR should be performed
using only the most sensitive assay, EPA-2 (Section 6.15).
2.2 Post Decontamination Phase - Sample Analyses for Viability: After samples have been
appropriately processed, they are cultured by either inoculating into nutrient rich broth (RV-PCR
procedures) or plating on sheep blood agar (SBA), culture procedures, to allow for germination of
viable spores.
2.2.1 RV-PCR Procedure
The RV-PCR is a combination of rapid broth culture and real-time PCR. Culturing the
samples allows the germination of viable B. anthracis spores recovered from processed
samples. Real-time PCR, via change in cycle-threshold (CT) value, offers a rapid
determination of the viability and identity of B. anthracis bacteria that grow from
germinated spores in broth culture. Samples (air filter, wipe, Sponge-Stick, swab,
vacuum sock or filter, or drinking water) are processed in multiple spore extraction and
wash steps.
Recovered spores are incubated in brain heart infusion (BHI) broth for optimum growth
of B. anthracis. After vortexing, an aliquot is withdrawn for baseline analysis. This is
the Time Zero (T0) aliquot and is stored at 4°C. Then the broth culture remaining in the
filter cup is incubated at 36°C for 9 hours on a rotary shaker incubator. After the broth
culture has incubated for 9 hours, another aliquot is withdrawn. This is the T9 aliquot.
Both the TO and T9 aliquots are processed to extract and purify total DNA. The T0 and T9
DNA extracts, in triplicate, are then analyzed in real-time PCR assay(s) to detect
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Detection of Bacillus anthracis in Environmental Samples
B. anthracis DNA. The CT values for both the T0 and T9 DNA extracts are recorded and
compared. Unless advised otherwise, real-time PCR should be performed using only the
most sensitive assay, EPA-2 (Section 6.15).
2.2.2 Culture Procedure
The culture option includes plating serial dilutions of the sample on a non-selective agar
SB A followed by rapid confirmation of typical isolated colonies using real-time PCR.
Unless advised otherwise, real-time PCR should be performed using only the most
sensitive assay, EPA-2 (Section 6.15).
3.0 Interferences and Contamination
3.1 Low recoveries of B. anthracis spores may be caused by the presence of high numbers of
competing or inhibitory organisms, background debris, or toxic substances (e.g., metals or
organic compounds).
3.2 Metals and organic compounds may also inhibit PCR reactions.
3.3 Problems related to sample processing, such as clogging of filters and inefficient extraction, may
also result in low spore recoveries.
4.0 Safety
Note: This protocol should not be misconstrued as a laboratory standard operating procedure
(SOP) that addresses all aspects of safety; the laboratory should adhere to their
established safety guidelines.
4.1 Laboratory Hazards
Direct contact of skin or mucous membranes with infectious materials, accidental parenteral
inoculation, ingestion, and exposure to aerosols and infectious droplets has resulted in B.
anthracis infection. Due to the infectious nature of this organism, all samples should be handled
using biosafety requirements as dictated by Biosafety in Microbiological and Biomedical
Laboratories [BMBL], 5th Edition, CDC 2009. (Reference 16.1) and/or organizational health and
safety plans.
4.2 Recommended Precautions
4.2.1 A biological safety level (BSL)-3 laboratory is required for handling and manipulating
samples and cultures presumptive for B. anthracis. B. anthracis analyses should be
conducted using BSL-3 practices, containment and facilities (BMBL, 5th Edition, CDC
2009. [Reference 16.1]). Additional biosafety and select agent information, as well as
statutory requirements for possession, use and transfer of select agents, can be found in
the Code of Federal Regulations (42 CFRpart 73).
4.2.2 All drinking water concentration activities should be performed within a BSL-3 facility
using BSL-3 practices. If a biological safety cabinet (BSC) is not used, due to space
limitations, approved respiratory equipment should be used while concentrating samples
within the BSL-3 suite. Caution should be used throughout the process (e.g., switching
carboys, manipulation of the apparatus, adding wash solutions) to minimize spills/leaks.
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Detection of Bacillus anthracis in Environmental Samples
Analysts should be properly trained prior to concentrating samples using the protocol
provided in Appendix A.
4.2.3 BSL-3 Practices
The laboratory supervisor must ensure that laboratory personnel demonstrate proficiency
in standard and special microbiological practices before working with BSL-3 agents. All
procedures involving manipulation of infectious material must be conducted within a
BSC (preferably Class II or Class III) or other physical containment device. Protective
clothing (e.g., laboratory coats, gloves and respirator) should be worn while processing
and analyzing samples. Personal protective equipment (PPE) should never be worn
outside the laboratory.
4.2.4 Disposable materials are recommended for sample manipulations.
4.2.5 The analyst must know and observe normal safety procedures required in a microbiology
laboratory while preparing, using and disposing of media, cultures, reagents and
materials. Analysts must be familiar with the operation of sterilization equipment.
4.2.6 Personal Protective Equipment (PPE)
• Laboratory personnel processing and conducting analyses of samples for B. anthracis
place themselves at risk for exposure. However, the use of appropriate PPE can reduce
the exposure risk. Laboratory personnel should familiarize themselves with the specific
guidance for levels of protection and protective gear developed by the U.S. Department
of Labor, Occupational Safety and Health Administration (OSHA), as provided in
Appendix B of 29 CFR 1910.120
(http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p
id=9767). In addition to OSHA guidance, the Centers for Disease Control and
Prevention (CDC) has developed recommendations for PPE based on BSL (Reference
16.1, http://www.cdc.gov/biosafety/publications/bmbl5/index.htm).
• Goggles or a face shield should be used for protection against splashes, spills and sprays.
Protective coats, gowns, smocks or uniforms designated for laboratory use must be worn
while working with samples and potentially contaminated materials. It may also be
necessary to use a powered air purifying respirator (PAPR) to reduce the risk of
inhalation. After use, protective clothing should be placed in sealed bags for appropriate
decontamination, disposal or laundering. Disposable gloves should be worn to protect
hands from contact with potentially contaminated samples. Wearing two pairs of gloves
may be appropriate, but should not compromise needed dexterity.
Note: Gloves should be removed appropriately to avoid contaminating hands and surfaces
between processing of each sample to prevent cross-contamination and disposed of
whenever they become visibly contaminated or the integrity of the gloves is
compromised. After all work with potentially infectious materials is completed, gloves
should be removed and hands should be washed with soap and water.
4.2.7 Depending on each laboratory's biosafety requirements, analysts may be required to be
vaccinated prior to working with samples that could contain B. anthracis.
4.2.8 This protocol does not address all safety issues associated with its use. Please refer to
BMBL, 5th Edition, CDC 2009. (Reference 16.1) for additional safety information. A
reference file of Material Safety Data Sheets (MSDS) should be available to all personnel
involved in analyses.
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Detection of Bacillus anthracis in Environmental Samples
5.0 Supplies and Equipment
Note: Refer to Appendix A for supplies and equipment for large volume drinking water
sample processing.
5.1 General Laboratory Supplies
5.1.1 Gloves (e.g, latex, vinyl, or nitrile)
5.1.2 Sterile gloves (e.g., latex, vinyl, or nitrile)
5.1.3 Bleach wipes (Dispatch® Cat. No. 69150 or equivalent)
5.1.4 Wipes
5.1.5 Ziplock bags (large -20" x 28", medium -12" x 16", small -7" x 8")
5.1.6 Sharps waste container
5.1.7 Absorbent pad
5.1.8 Medium and large biohazard bag(s) and rubber band(s)
5.1.9 Sterile scalpels
5.1.10 Sterile stainless steel scissors
5.1.11 Squeeze bottle with 70% isopropyl alcohol
5.1.12 Squeeze bottle with deionized (DI) water
5.1.13 Autoclave tape
5.1.14 Autoclave bags, aluminum foil, or kraft paper
5.1.15 Large photo-tray or similar tray for transport of racks
5.1.16 Laboratory marker
5.1.17 Timer
5.1.18 Disposable aerosol barrier pipet tips: 1000 \\L, 200 \\L, 10 \\L (Rainin Cat. No.
SR-L1000F, SR-L200F, GP-10F or equivalent)
5.1.19 1.5 mL Eppendorf Snap-Cap Microcentrifuge Biopur® Safe-Lock® tubes (Fisher
Scientific Cat. No. 05-402-24B or equivalent)
5.1.20 50 mL conical tubes (Fisher Scientific Cat. No. 06-443-18 or equivalent)
5.1.21 15 mL conical tubes (Fisher Scientific Cat. No. 339650 or equivalent)
5.1.22 250 mL and 1 L filter systems, polyethersulfone (PES), 0.2 \\m (Fisher Scientific Cat.
No. 09-741-04, 09-741-03 or equivalent)
5.1.23 0.1 urn Ultrafree-MC, VV filter unit (Millipore Cat. No. UFC30VVOO or equivalent)
5.1.24 Tubes, sterile 2 mL DNase, RNase-free, gasketed, screw caps (National Scientific Cat.
No. BC20NA-PS or equivalent)
5.1.25 Glass Petri dishes, 100 * 15 mm
5.1.26 Glass beads, acid washed, 106 \\m and finer (Sigma Cat. No. G4649 or equivalent)
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Detection of Bacillus anthracis in Environmental Samples
5.1.27 Glass beads, acid washed, 425 - 600 (im and finer (Sigma Cat. No. G8772 or equivalent)
5.1.28 PCR 8 cap strips (VWR Cat. No. 83009-684 or equivalent)
5.1.29 Microcon® Centrifugal Filter Devices, Micron YM-100, blue Microcon® filters,
(Amicon/Millipore Cat. No. 42413)
5.1.30 Wide mouth screw cap containers (Fisher Scientific Cat. No. 4-375-459 or equivalent)
5.1.31 Gauze wipes, 2" x 2" 50% rayon/50% polyester (Kendall™ Versalon™ Cat. No. 8042 or
equivalent)
5.1.32 Air filters, 37 mm, Fluoropore™ (Millipore Cat. No. FSLW04700 or equivalent)
5.1.33 Swabs, macrofoam (VWR Cat. No. 10812-016 or equivalent)
5.1.34 Vacuum socks (Midwest Filtration Co. Cat. No. FAB-07-03-006PS or equivalent)
5.1.35 Vacuum filters (3M Forensic, Precision Data Products Cat. No. FF-1 with 4" diameter
filter or equivalent)
5.1.36 Sponge-Stick sampling tools (3M Inc. Cat. No. SSL100 or equivalent).
5.2 Supplies for RV-PCR Analysis
5.2.1 30 mL screw cap tubes (E&K Scientific Cat. No. EK-T324S or equivalent)
5.2.2 Disposable nylon forceps (VWR Cat. No. 12576-933 or equivalent)
5.2.3 Monofilament polyester mesh disc (McMaster Carr Cat. No. 93185T17 or equivalent) or
2" x 2" cut squares from mesh sheets (McMaster Carr Cat. No. 9218T13 or equivalent)
5.2.4 Whatman™ Autocup™, filter cups (VWR Cat. No. 1602-0465 or equivalent)
5.2.5 Polyethylene caps, blue with pull-tabs (McMaster Carr Cat. No. 94075K56 or
equivalent), for vortexing and incubation steps
5.2.6 50 mL Tube Cap (E&K Scientific, Cat. No. T3251-C or equivalent)
5.2.7 Polyethylene quick turn tube fittings (Ark-Plas Products Cat. No. 51525K365 or
equivalent)
5.2.8 50 mL conical tubes, skirted, sterile (VWR Cat. No. 82050-322 or equivalent)
5.2.9 Disposable serological pipets: 25 mL, 10 mL, 5 mL
5.2.10 Single 50 mL conical tube holder (Bel-Art Cat. No. 187950001 or equivalent)
5.2.11 Screw cap tubes, 2 mL (VWR Cat. No. 89004-298 or equivalent)
5.2.12 96-well tube rack(s) for 2 mL tubes (8 x 12 layout) (Bel-Art Cat. No. 188450031 or
equivalent)
5.2.13 2 mL Eppendorf tubes (Fisher Scientific Cat. No. 05-402-24C or equivalent)
5.2.14 96-well 2 mL tube rack (8 x 12 format) (Bel-Art Cat. No. 188450031)
5.3 Supplies for Real-time PCR Analysis
5.3.1 96-well PCR plates (ABI Cat. No. 4346906 or equivalent)
5.3.2 96-well plate holders, Costar®, black (VWR Cat. No. 29442-922 or equivalent)
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Detection of Bacillus anthracis in Environmental Samples
5.3.3 Edge seals for 96-well PCR plates (Adhesive Plate Sealers, Edge Bio Cat. No. 48461 or
equivalent)
5.3.4 Foil seals for 96-well PCR plates (Polar Seal Foil Sealing Tape, E& K Scientific Cat. No.
T592100 or equivalent) - for longer storage of the plates
5.3.5 Optical seals (ABI Cat. No. 4311971 or equivalent)
5.4 Supplies for Culture
5.4.1 Petri dishes, sterile, disposable, 100 x 15 mm
5.4.2 Inoculating loops and needles, sterile, disposable
5.4.3 Disposable cell spreaders (such as L-shaped, Fisher Scientific Cat. No. 03-392-150 or
equivalent)
5.4.4 MicroFunnel™ Filter Funnels, 0.45 (im pore-size (VWR Cat. No. 55095-060 or
equivalent)
5.4.5 Racks for 15 mL and 50 mL centrifuge tubes
5.4.6 Sterile, plastic, screw cap 50 mL centrifuge tubes (Becton, Dickinson and company [BD]
Cat. No. 352070 or equivalent)
5.4.7 Sterile, plastic, screw cap 15 mL centrifuge tubes (BD Cat. No. 352097 or equivalent)
5.4.8 Pipet tips with aerosol filter for 1000 (iL and 100 (iL (Rainin Cat. No. SR-L1000F and
GP-100F or equivalent)
5.4.9 Biotransport carrier (Nalgene® , Thermo Scientific Cat. No. 15-251-2 or equivalent)
5.5 Equipment
5.5.1 Biological Safety Cabinet (BSC) - Class II or Class III
5.5.2 PCR preparation hood (optional)
5.5.3 Shaker incubator for RV-PCR (Thermo Scientific, MaxQ™ 4000 Cat No. SHKE4000 or
equivalent) and Universal 18" x 18" shaker platform (Thermo Scientific, MaxQ™ Cat.
No. 30110)
5.5.4 Balance, analytical, with Class S reference weights, capable of weighing 20 g ± 0.001 g
5.5.5 Applied Biosystems® (ABI) 7500 Fast Real-Time PCR System (Life Technologies™)
5.5.6 Refrigerated centrifuge with PCR plate adapter and corresponding safety cups
(Eppendorf Cat. No. 5804R, 5810R or equivalent) or PCR plate spinner (placed in BSC)
(VWR, Cat. No. 89184-608 or equivalent)
5.5.7 Refrigerated micro-centrifuge for Eppendorf tubes with aerosol-tight rotor (Eppendorf
Cat No. 5415R or equivalent)
5.5.8 Filter cup manifold-top and bottom for RV-PCR (DV Manufacturing. Cat. No. DVM-
OSH-24 and DVM-BCP-24)
5.5.9 Allen wrench for manifold for RV-PCR (9/64 Hex key)
5.5.10 Capping tray for RV-PCR (DV Manufacturing Cat. No. DVM-LB-24) and screws to
attach to shaker platform (DV Manufacturing)
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Detection of Bacillus anthracis in Environmental Samples
5.5.11 30 mL tube rack for RV-PCR (DV Manufacturing Cat. No. DVM-24 VC)
5.5.12 Vacuum pump with gauge (Cole Farmer® Model EW-07061-40 or equivalent) or vacuum
source capable of < 10 pounds per square inch (psi)
5.5.13 Vacuum pump filters for pump (Acrovent™ Cat. No. 4249 or equivalent)
5.5.14 Vacuum trap accessories
5.5.15 Platform vortexer for RV-PCR (VWR Cat. No. 588 16-1 15 or equivalent) with velcro
straps
5.5.16 Single-tube vortexer (Fisher Scientific Cat. No. 02-215-365 or equivalent)
5.5.17 Heating block for RV-PCR (VWR Cat. No. 12621-096 or equivalent) and 2 mL tube
blocks (VWR Cat. No. 12985-048 or equivalent) or water bath set at 95°C
5.5.18 Single-channel micropipettors (1000 jiL, 200 nL,100 (iL, 20 (iL, 10
5.5.19 Serological pipet aid
5.5.20 Dynamag™ magnetic racks for RV-PCR (Invitrogen® Cat. No. 123 -2 ID or equivalent)
5.5.21 Incubator(s), microbiological type, maintained at 37.0°C
5.5.22 Autoclave or steam sterilizer, capable of achieving 121°C (15 psi) for 30 minutes
5.5.23 Manifold incubator rack to hold up to 4 manifold/capping trays (DV Manufacturing Cat.
No. 1701 190) and/or peg kit for securing individual manifold/capping trays to the
shaking incubator platform (Shaker Kit, DV Manufacturing Cat. No. 1701 189) for
RV-PCR
5.5.24 Cold block for 2 mL tubes (Eppendorf Cat. No. 3880 001.018 or equivalent)
5.5.25 Bead-beater (BioSpec Products, Inc. Cat. No. 693 [8 place] or 607 [16 place] or
equivalent)
5.5.26 Tube racks, 80 place (VWR Cat. No. 30128-282 or equivalent)
5.5.27 40 kHz Sonicator bath (Branson Ultrasonic Cleaner Model 1510, Process Equipment and
Supply, Inc. Cat. No. 952-1 16 or equivalent)
5.5.28 Stomacher® 400 Circulator (Seward Cat. No. 0400/00 1/AJ or equivalent) with closure
bags (Cat. No. BA6141/CLR or equivalent) and rack (Cat. No. BA6091 [1 place] and
BA6096 [10 place] or equivalent)
6.0 Reagents and Standards
6.1 Reagent-grade chemicals must be used in all tests. Unless otherwise indicated, reagents shall
conform to the specifications of the Committee on Analytical Reagents of the American
Chemical Society (Reference 16.2). For suggestions regarding the testing of reagents not listed
by the American Chemical Society, see 'AnalaR' Standards for Laboratory Chemicals, BDH
Ltd., Poole, Dorset, U.K. (Reference 16.3); and United States Pharmacopeia and National
Formulary 24, United States Pharmacopeial Convention, Md. (Reference 16.4).
10 December 2012
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Detection of Bacillus anthracis in Environmental Samples
6.2 10X Wash Buffer for RV-PCR (250 mM KH2PO4, pH 7.4)
6.2.1 Composition:
KH2PO4 34 g
Reagent-grade water ~1 L
6.2.2 Dissolve KH2PO4in 500 mL of reagent-grade water. Addition of NaOH is required if
reagent-grade water has a low pH (pH ~5). Add 1 N NaOH to bring to pH 7.4 (> 100 mL
of 1 N NaOH). Bring volume to 1 L with reagent-grade water. Filter sterilize using 250
mL, 0.22 (im PES filtering system. Store solution at 4°C until time of use for a
maximum of 90 days.
6.3 IX Wash Buffer for RV-PCR (Low Salt Buffer)
6.3.1 Composition:
1 OX wash buffer lOOmL
Reagent-grade water 900 mL
6.3.2 Mix with magnetic stirrer: when mixed, measure pH. Final pH should be 7.4. Filter
sterilize using a 1 L, 0.22 (im PES filtering system with disposable bottle. Store solution
at 4°C until time of use for a maximum of 90 days.
6.4 Tween® 80 (Fisher Cat. No. T164 or equivalent)
6.5 Extraction Buffer with Tween® 80 for RV-PCR
6.5.1 Composition:
1 OX wash buffer 1 mL
200 proof ethanol 300 mL
Tween® 80 0.5 mL
Reagent-grade water 698.5 mL
6.5.2 Add 10X wash buffer, ethanol and Tween® 80 to 500 mL of reagent-grade water and mix
well. Bring volume to 1 L with reagent-grade water; mix well. Filter sterilize using a 1
L, 0.22 (im PES filtering system with disposable bottle. Store solution at 4°C until time
of use for a maximum of 90 days.
6.6 Extraction Buffer without Tween® 80 for RV-PCR
6.6.1 Composition:
10X wash buffer 1 mL
200 proof ethanol 300 mL
Reagent-grade water 699 mL
6.6.2 Add 10X wash buffer and ethanol to 500 mL of reagent-grade water mix well. Bring
volume to 1 L with reagent-grade water; mix well. Filter sterilize using a 1 L, 0.22 (im
PES filtering system with disposable bottle. Store solution at 4°C until time of use for a
maximum of 90 days.
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Detection of Bacillus anthracis in Environmental Samples
6.7 High Salt Wash Buffer for RV-PCR
6.7.1 Composition:
KH2PO4 28.2 g
Reagent-grade water 1 L
6.7.2 Dissolve KH2PO4 in 500 mL of reagent-grade water. Addition of NaOH is required if
reagent-grade water has low pH (pH ~5). Add 1 M NaOH to bring to pH 6.0 (> 100 mL
of 1 M NaOH). Bring volume to 1 L with reagent-grade water. Filter sterilize using a 1
L, 0.22 (im PES filtering system with disposable bottle. Store solution at 4°C until time
of use for a maximum of 90 days.
6.8 70% Ethanol for RV-PCR - Aseptically mix 70 mL of ethanol (100%) with 3 0 mL of sterile PCR-
grade water. Dispense into 2-3, sterile 50 mL conical tubes and store at 4°C, for a maximum of
one week. Unopened tubes may be stored for up to one month at 4°C.
6.9 PCR-grade water, sterile (Teknova Cat. No. W3350 or equivalent)
6.10 Phosphate buffered saline Tween® 20 (PBST) buffer for RV-PCR (Teknova Cat. No. P0201 or
equivalent)
6.11 PBST buffer with 0.005% Anti-Foam reagent (Section 6.14) for Ultrafiltration secondary water
sample processing; prepare aseptically mix well by vortexing before use.
6.12 0.1 M Sodium Phosphate/10 mM EDTA buffer/0.01% Tween-20, pH = 7.4 (Teknova Cat. No.
S2216 or equivalent)
6.13 TE buffer (IX Tris-HCl-EDTA [Ethylenediaminetetraacetic acid]) buffer, pH 8.0 (Fisher
Scientific Cat. No. BP2473-500 or equivalent)
6.14 Promega reagents for DNA extraction and purification procedure for RV-PCR:
• MagneSil® Blood Genomic, Max Yield System, Kit (Promega Cat. No. MD1360; VWR Cat.
No. PAMD1360)
• Salt Wash (VWR Cat. No. PAMD1401 or equivalent)
• Magnesil Paramagnetic Particles (PMPs) (VWR Cat. No. PAMD 1441 or equivalent)
• Lysis Buffer (VWR, Cat. No. PAMD 1392 or equivalent)
• Elution Buffer (VWR Cat. No. PAMD 1421 or equivalent)
• Alcohol Wash, Blood (VWR Cat. No. PAMD 1411 or equivalent)
• Anti-Foam Reagent (VWR Cat. No. PAMD 1431 or equivalent)
6.15 TaqMan® Fast Advanced PCR Master Mix (Life Technologies™ Cat. No. 4444557)
6.16 Primers and probe for EPA-2 PCR assay targeting the capB gene on the pXO2 plasmid (Francy et
al, 2009 [Reference 16.5])
• Forward Primer (BA-EPA-2F) - 5' -TGCGCGAATGATATATTGGTTT-3'
• Reverse Primer (BA-EPA-2R) - 5' -GCTCACCGATATTAGGACCTTCTTTA-3'
• Probe (BA-EPA-2Pr) - 5' -6FAM-TGACGAGGAGCAACCGATTAAGCGC-BHQ1 -3'
12 December 2012
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Detection of Bacillus anthracis in Environmental Samples
6.17 Optional Real-time PCR Assays
EPA-1 targeting thepagA gene on pXOl plasmid (Francy et al, 2009 [Reference 16.5])
• Forward Primer (BA-EPA-1F) - 5' -GCGGATAGCGGCGGTTA-3'
• Reverse Primer (BA-EPA-1R) - 5' -TCGGTTCGTTAAATCCAAATGC-3'
• Probe (BA-EPA-IPr) -
5' -6FAM-ACGACTAAACCGGATATGACATTAAAAGAAGCCCTTAA-BHQ1 -3'
BC3 targeting a hypothetical gene on the chromosome of B. anthracis
• Forward Primer (BA-BC3-F) - 5'-TTTCGATGATTTGCAATGCC-3'
• Reverse Primer (BA-BC3-R) - 5'-TCCAAGTTACAGTGTCGGCATATT-3'
• Probe (BA-BC3-Pr) - 5'-6FAM-ACATCAAGTCATGGCGTGACTACCCAGACTT-BHQ1 -3'
6.18 Trypticase™ Soy Agar with 5% Sheep Blood (SBA)
6.18.1 The use of commercially prepared media plates is recommended (VWR Cat. No. 90001-
276 or 90001-282 or equivalent), however dehydrated media (BBL™ Cat. No. 227300 or
equivalent), with the addition of sheep blood (Oxoid Cat. No. SR0051 or equivalent),
may be used. If commercially prepared media are not available, prepare media using
procedures in Sections 6.17.2 - 6.17.4.
6.17.2 Composition:
Tryptone H 15 g
Soytone 5 g
Sodium chloride 5 g
Agar 12 g
Sheep blood 50 mL
Reagent-grade water -900 mL
6.18.3 Add reagents except sheep blood to 850 mL of reagent-grade water and mix thoroughly
using a stir bar and hot plate. Boil for 1 minute with rapid stir bar agitation to dissolve
completely. Adjust pH to 7.3 ± 0.2 with 1.0 N HC1 or 1.0 N NaOH and bring to 950 mL
with reagent-grade water. Autoclave at 121°C (15 psi) for 15 minutes. Do not overheat.
Cool to 45°C - 50°C in a water bath.
6.18.4 Prepare plates by aseptically adding 50 mL of sterile sheep blood (5.0% final
concentration) to the cooled media and mix well. Aseptically pour 12-15 mL into each
15 x 100 mm sterile Petri dish. Store at 4°C for a maximum of two weeks.
13 December 2012
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Detection of Bacillus anthracis in Environmental Samples
6.19 Brain Heart Infusion Broth for RV-PCR (BHI broth, Fisher Scientific Cat. No. DF0037-15-0)
6.19.1 Composition:
Calf brains, infusion from 200 g 7.7g
Beef heart, infusion from 250 g 9.8g
Proteose peptone lO.Og
Sodium chloride 5.0 g
Disodium phosphate (Na2HPO4) 2.5 g
Dextrose 2.0 g
Reagent-grade water l.OL
6.19.2 Add reagents to 1 L of reagent-grade water, mix thoroughly and heat to dissolve
completely. Autoclave at 121°C (15 psi) for 15 minutes. Final pH should be 7.4 ± 0.2.
Store at 4°C for a maximum of three months in screw cap containers.
6.20 10% Bleach-pH amended (prepared daily)
6.20.1 Prepare bleach solution by adding 1 part bleach, 1 part acetic acid and 8 parts reagent-
grade water as described below.
6.20.2 Add 2 parts water to 1 part bleach, then add 5% acetic acid (1 part) and remaining water
(6 parts). Measure pH and add bleach (to increase pH) or acetic acid (to decrease pH) as
needed to obtain a final pH between 6 and 7. A pH meter should be used to measure pH
as opposed to pH strips or kit. When mixed, place a lid on the mixture to reduce chlorine
escape and reduce worker exposure.
7.0 Calibration and Standardization
7.1 Check temperatures in incubators twice daily with a minimum of four hours between each reading
to ensure operation within stated limits. Record the temperature in a log book.
7.2 Check temperature in refrigerators/freezers at least once daily to ensure operation is within stated
limits of the method. Record daily measurements in a refrigerator/freezer log book.
7.3 Check thermometers including those on instrumentation (e.g., digital display) at least annually
against a National Institute of Standards and Technology (NIST) certified thermometer or one that
meets the requirements of NIST Monograph SP 250-23. Check columns for breaks.
7.4 Calibrate pH meter prior to each use with two of three standards (e.g., pH 4.0, 7.0 or 10.0) closest
to the range being tested.
7.5 Micropipettors should be calibrated at least annually and tested for accuracy on a weekly basis.
7.6 Follow manufacturer instructions for calibration of real-time PCR instruments.
7.7 Re-certify BSCs annually. Re-certification must be performed by a qualified technician.
7.8 Autoclave maintenance should be conducted at least annually. Autoclave temperature and total
sterilization cycle time should be checked on a quarterly basis. Record the data in a log book.
Spore strips or spore ampules should be used monthly as bioindicators to confirm sterilization.
14 December 2012
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Detection of Bacillus anthracis in Environmental Samples
7.9 Refrigerated centrifuges should be checked to confirm temperature and revolutions per minute
(rpm) on a quarterly basis. Record the data in a log book.
8.0 Quality Control (QC)
8.1 Each laboratory that uses this protocol is required to operate a formal quality assurance (QA)
program that addresses and documents instrument and equipment maintenance and performance,
reagent quality and performance, analyst training and certification, and records storage and
retrieval. International Organization for Standardization (ISO)/International Electrotechnical
Commission (IEC) 17025 (International Standard: General requirements for the competence of
testing and calibration laboratories, Section Edition 2005-05-15) provides a quality framework that
could be used to develop a formal QA program.
8.2 Sample integrity — Samples should be checked for integrity (e.g., improperly packaged,
temperature exceedance, leaking). Samples may be rejected if the integrity has been
compromised. Alternately, if sample integrity has been compromised it may be analyzed and the
data qualified and marked accordingly (e.g., sample exceeded temperature during transport - data
is flagged and marked as exceeding temperature), so that a decision can made regarding whether
the data should be considered valid/invalid.
8.3 Analyst qualifications — Only those analysts that have been trained and have demonstrated
proficiency with these analytical techniques should perform this procedure.
8.4 Proficiency testing (PT) — The laboratory should have analysts analyze test samples annually at a
minimum to ensure they are maintaining proficiency. In addition, analysts should analyze PT
samples to demonstrate proficiency prior to analyzing field samples. For laboratories not routinely
using this protocol, analysts should analyze PT samples biannually. In the event of a PT failure
the laboratory should identify and resolve any issues and then request and analyze additional PT
samples. Field samples should not be analyzed until the laboratory passes the PT.
8.5 Media sterility check — The laboratory should test media sterility by incubating a single unit (tube
or Petri dish) from each batch of medium (BHI broth or SB A) at 37°C ± 2°C for 24 ± 2 hours and
observe for growth. Absence of growth indicates media sterility. On an ongoing basis, the
laboratory should perform a media sterility check every day that samples are analyzed.
8.6 PCR: Positive control (PC) — The laboratory should analyze a PC in triplicate reactions with each
PCR run. Prepare the PC at a concentration of 50 pg of purified B. anthracis total DNA per 5 (iL
of PCR-grade water. All PCs should result in a CT < 40 and replicates should be within ± 1 CT of
each other.
8.7 Culture: Positive control (PC) — The laboratory should analyze PCs (known quantity of viable
spores) to ensure that all media and reagents are performing properly. PCs should be analyzed
whenever a new batch of media or reagents is used. On an ongoing basis, the laboratory should
run a PC every day that samples are analyzed.
8.8 External inhibition control (EIC) 50 pg genomic DNA from B. anthracis Ames — The laboratory
should analyze an EIC for site characterization phase sample DNA extracts to determine if the
matrix is causing inhibition potentially resulting in false negative results. Prepare the EIC at a
concentration of 50 pg of purified B. anthracis DNA per 1 \\L of PCR-grade water. Using a 10 \\L
pipettor, carefully add 1 \\L of the DNA to the EIC wells on a PCR plate and then add 5 \\L of
sample DNA extract to each well and mix thoroughly. The PCR results from the PC and EICs
15 December 2012
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Detection of Bacillus anthracis in Environmental Samples
(both containing 50 pg of B. anthracis DNA) are then compared. Lower or similar CT values for
the EIC indicate there is no inhibition. A higher CT value for the EIC (>3 CT values) is indicative
of matrix inhibition.
Note: To minimize cross contamination the EICs should not be placed next to the field samples when
setting up the PCR plate.
8.9
8.10
8.11
8.12
No template controls (NTC) — The laboratory should analyze NTCs (5 (iL of PCR-grade water is
added to the NTC wells on a PCR plate in place of the DNA or the sample DNA extract) to ensure
that reagents are not contaminated. On an ongoing basis, the laboratory should analyze NTCs in
triplicate PCR reactions with each PCR run. The negative controls (NTCs) must not exhibit
fluorescence above the background level (i.e., no CT value). If CT values are obtained as a result
of a possible contamination or cross-contamination, prepare fresh PCR Master Mix and repeat the
analysis.
Field blank — The laboratory should request that the sampling team provide a field blank with
each batch of samples. A field blank is defined as either a sample collection tool (e.g., wipe,
swab) or sterile reagent-grade water that is taken out to the field, opened and exposed to the
environment, but not used to collect a sample, and then placed in a bag and sealed and transported
to the laboratory along with the field samples. The field blank is treated as a sample in all
respects, including exposure to sampling location conditions, storage, preservation and all
analytical procedures. Field blanks are used to assess any contamination contributed from
sampling location conditions, transport, handling and storage. The laboratory should process and
analyze this control along with each batch of environmental samples. The field blanks should not
exhibit fluorescence (i.e., no CT value).
Sample processing negative control (PNC) or method blank — The laboratory should process and
analyze a PNC in the same manner as a sample to verify the sterility of equipment, materials and
supplies. Absence of growth indicates lack of contamination from the target organism. Please
refer to Table 1 for appropriate PNC.
Table 1. Sample Processing Negative Controls
Matrix
Wipes
Swabs
Vacuum socks/filters
Air filters
Sponge-Sticks
Drinking water and decontamination
waste water
PNC
Clean (unused) wipe
Clean (unused) swab
Clean (unused) vacuum sock/filter
Clean (unused) air filter
Clean (unused) Sponge-Stick
100 mL of sterile reagent-grade water
For RV-PCR based analysis, the T0 and T9 extracts are analyzed (in triplicate). PCR positive and
negative controls must be analyzed using the same preparation of the PCR Master Mix and must
be run on the same 96-well plate as the T0 and T9 extracts.
16
December 2012
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Detection of Bacillus anthracis in Environmental Samples
9.0 Site Characterization Procedures
For sample analyses during the site characterization phase of the response to an anthrax event,
only real-time PCR based analytical procedures will be used. Accordingly, this section includes
appropriate sample processing and real-time PCR procedures.
Acceptable sample types: Gauze wipes (2" x 2" 50% rayon/50% polyester), air filters (37 mm),
swabs (macrofoam), vacuum socks (large dust collection sample bags, 9 1/8" x 4", mean pore size
6.7 (im), vacuum filters (4" diameter filter), Sponge-Stick sampling tools, drinking water and
decontamination waste water.
Note: For laboratories with RV-PCR capability please follow the sample processing procedures
for spore recovery and concentration as outlined below (Section 9.1). For all other
laboratories, either the same procedures (Section 9.1) could be followed or those
described for culture analyses as outlined in Sections 11.1 -11.5 could be used.
9.1 Sample Processing for Laboratories With RV-PCR Capability
Note: Sterile gloves should be used and changed between samples and as indicated below.
Prepare monofilament polyester mesh (Section 5.2.3) supports by cutting 2" x 2" squares using
sterile scissors and place squares into a clean ziplock bag. Since the supports are not sterilized
prior to use, ensure that the working surface has been disinfected and sterile gloves are worn
during the process.
Fill sample tube rack with 30 mL or 50 mL screw cap conical tubes as appropriate. All sample
types (except water samples) may be placed behind a mesh support in the tube to prevent
interference from pipetting activities and to improve efficiency of spore extraction during
vortexing. Using two pairs of sterile forceps, coil the mesh support and then grasp both ends of
the coil with one pair of forceps. Place the support into the tube by holding the sample to the side
of the tube with one pair of sterile forceps and placing the coiled mesh support on top with the
other set of forceps.
9.1.1 Wipe and Air Filter Samples
Place mesh support over wipe or air filter samples in 30 mL tube by holding the wipe or
air filter to the side of the tube with sterile forceps and placing the coiled mesh support on
top (Section 9.1). Ensure the sample and mesh are in the bottom half of the tube
(avoiding the conical portion). Change gloves in between each sample. The support
keeps the wipe or air filter from interfering with pipetting activities and also improves
efficiency of spore extraction during vortexing. Proceed to Section 9.1.7.
9.1.2 Vacuum Samples (Socks and Filters)
For vacuum socks, using sterile scissors, cut the top blue portion off and discard prior to
folding the sock from the top opening down. Make four 1/2" folds in order to reduce the
sock size to about 1" x 2". Cut the sock five times above the 30 mL tube using scissors,
making sure to cut through all the folds. Place cut, folded sock in bottom half of tube
(avoiding conical portion) and using two pairs of sterile forceps, place the coiled mesh
support on top of sock (Section 9.1). Bleach the BSC working surface and don a fresh
pair of gloves in between samples. Proceed to Section 9.1.7.
17 December 2012
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Detection of Bacillus anthracis in Environmental Samples
Note: The sample processing procedure provided is for up to 1 tablespoon (~1 g of test dust)
of debris per sock sample. If socks received contain higher levels of debris, follow
procedure in Section 11.4.1.
For vacuum filters, ensure that the exposed filter surface (with debris) is facing up and
carefully cut through the evidence tape with a sterile scalpel in order to remove the top of
the cartridge. Using a pair of sterile forceps, transfer large pieces of debris into the
appropriate 50 mL tube, then fold filter in half with dirty, exposed filter side in, and then
fold in half again in order to fit it into the 50 mL tube. Place folded filter in bottom half
of tube (avoiding conical portion) and using two pairs of sterile forceps place the coiled
mesh support on top of filter (Section 9.1). Proceed to Section 9.1.7.
9.1.3 Sponge-Stick Sampling Tools
• If the Sponge-Sticks/wipes are not in Stomacher® bags, aseptically transfer each sample
to a Stomacher® bag using sterile forceps. Change forceps between samples.
• Add 90 mL of phosphate buffered saline with Tween® 20 (PBST) to each bag. Set
Stomacher® (Section 5.5.28) to 260 rpm.
• Place a bag containing a sample into the Stomacher® (Section 5.5.28) so the Sponge-
Stick/wipe rests evenly between the homogenizer paddles and stomach each sample for 1
minute.
• Open the door of the Stomacher® (Section 5.5.28) and remove the bag. Grab the wipe
from the outside of the bag with hands. With the bag closed, move the Sponge-
Stick/wipe to the top of the bag while using hands to squeeze excess liquid from the
Sponge-Stick/wipe.
• Open the bag, remove and discard the Sponge-Stick/wipe using sterile forceps.
• Repeat steps described above for each sample.
• Allow bags to sit for 10 minutes to allow elution suspension foam to settle.
• Gently mix the elution suspension in the Stomacher® bag up and down 3 times with a
sterile 50 mL pipet. Remove half of the suspension volume (-45 mL) and place it in a 50
mL screw capped centrifuge tube. Place the remaining suspension (~45 mL) into a
second 50 mLtube.
• Record suspension volumes on tubes and data sheet.
• Process elution suspension for each sample as described above.
• Place 50 mL tubes into sealing centrifuge buckets and decontaminate centrifuge buckets
before removing them from the BSC.
• Centrifuge tubes at 3500 x g, with the brake off, for 15 minutes in a swinging bucket
rotor.
Note: A higher x g is preferred as long as the speed is within the tube specifications.
• Remove the supernatant from each tube with a 50 mL pipet and discard leaving
approximately 3 mL in each tube. The pellet may be easily disturbed and not visible, so
keep the pipet tip away from the tube bottom. Use a sterile 50 mL pipet for each sample.
• Set the vortexer (Section 5.5.16) to high intensity. Set the sonicator water bath to high.
18 December 2012
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Detection of Bacillus anthracis in Environmental Samples
• Vortex the tubes for 30 seconds and transfer the tubes to the sonicator bath and sonicate
for 30 seconds. Repeat the vortex and sonication cycles twice.
• Remove suspension from one tube with a sterile 5 mL pipet and combine it with the
suspension in the other tube from the same sample. Measure final volume of suspension
with 5 mL pipet and record the result on the tube and data sheet.
• Repeat vortexing and sonication steps for each sample.
• Proceed to Section 9.1.19.
9.1.4 Swabs
Place swab into the 30 mL tube and cut handle with sterile scissors if necessary to fit into
the tube. Using sterile forceps, place the coiled mesh support over the swab (Section
9.1). Proceed to Section 9.1.7.
9.1.5 Water Samples (Large Volume [10 L -100 L], Drinking Water)
Please see Appendix A for primary (Section 2.0) and secondary (Section 3.0)
concentration of large volume (10 L - 100 L) water samples. For water samples < 10 L,
please refer to Appendix A, Section 3.0, secondary concentration.
• Add 15 mL of PBST buffer to the 50 mL conical tube with membrane (Appendix A,
Section 3.5).
• Set vortexer (Section 5.5.16) to high intensity.
• Vortex membrane in 10 second bursts for 2 minutes to dislodge spores.
• Remove membrane and centrifuge at 3500 x g5 with the brake off, for 30 minutes at 4°C.
Note: A higher x g is preferred as long as the speed is within the tube specifications.
• Remove 12 mL of the supernatant without disturbing/dislodging the pellet; resuspend the
pellet by vortexing in the remaining volume.
• Use a 0.5 mL aliquot for DNA extraction using bead-beating, as described in Section 9.2.
9.1.6 Water Samples (Small Volume [< 50 mL], Surface or Drinking Water)
• Transfer 30 mL of water sample into a 50 mL screw cap conical tube.
• Add 10 mL of PBST buffer (Section 6.10) and mix by vortexing for 30 seconds.
• Centrifuge at 3500 x g5 with the brake off, for 30 minutes at 4°C.
Note: A higher x g is preferred as long as the speed is within the tube specifications.
• Remove 37 mL of the supernatant without disturbing/dislodging the pellet. The volume
of supernatant remaining should not be below the conical portion of the tube. Resuspend
the pellet by vortexing in the remaining volume.
• Use a 0.5 mL aliquot for DNA extraction using bead-beating, as described in Section 9.2.
9.1.7 Add 20 mL (5 mL for swabs) of cold (4°C) extraction buffer with Tween® 80 to
environmental samples (Sections 9.1.1, 9.1.2, 9.1.4) placed in 30 mL tubes in tube rack.
Use a new serological pipet to transfer buffer from a sterile, 250 mL screw capped bottle
to each tube (keep bottle cap loosely over opening between transfers). Uncap one tube at
19 December 2012
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Detection of Bacillus anthracis in Environmental Samples
a time, add 20 mL extraction buffer with Tween® 80, close tube, and place it back in tube
rack. Repeat for each sample tube. Check that all caps are on tubes securely. Label
tubes, as appropriate, and document location in rack.
9.1.8 Place tube rack in plastic bag, seal, bleach bag and double bag, prior to transferring to
platform vortexer (outside BSC).
9.1.9 Vortex samples for 20 minutes on platform vortexer (Section 5.5.15), with speed set to 7.
9.1.10 After vortexing, transfer sample tube rack to BSC. Remove tube rack from plastic bag.
9.1.11 Vortex one sample tube on single-tube vortexer (Section 5.5.16), in the BSC, for 3-5
seconds. For samples containing large amounts of debris, let sample sit for 30 seconds to
allow large particles to settle prior to aliquoting.
9.1.12 Uncap tube. Using a 25 mL serological pipet, transfer as much liquid volume as possible
(while avoiding any particles) to a fresh appropriately labeled 50 mL conical tube and
place in tube rack. Dispose pipets in waste container. Cap sample tube and place tube
back in rack. Change gloves.
9.1.13 Repeat Sections 9.1.11 -9.1.12 for each sample tube.
9.1.14 Perform second spore extraction. Uncap one sample tube at a time.
9.1.15 Add 14 mL (5 mL for swabs) of cold (4°C) extraction buffer without Tween® to each
sample tube, one at a time, with a new 25 mL serological pipet and a fresh pair of gloves
for each sample. Keep buffer bottle loosely covered between transfers. Recap sample
tube after buffer addition.
9.1.16 After adding extraction buffer to all tubes, check that all caps are on securely. Place rack
in plastic bag, seal and bleach bag. Transfer bagged tube rack to platform vortexer
(Section 5.5.15) outside BSC.
9.1.17 Vortex rack for 10 minutes, with speed set to 7.
9.1.18 Repeat Sections 9.1.11-9.1.12.
9.1.19 Centrifuge the 50 mL conical tube containing the combined suspension at 3500 x g5 with
the brake off, for 30 minutes at 4°C.
Note: A higher x g is preferred as long as the speed is within the tube specifications.
9.1.20 Leaving approximately 3 mL in the tube, carefully discard the supernatant using a
serological pipet without disturbing/dislodging the pellet. Ensure that the volume of
liquid remaining is not below the conical portion of the tube. Resuspend the pellet by
vortexing.
9.1.21 Add 25 mL of Phosphate/EDTA/Tween buffer (Section 6.11) and mix the suspension by
vortexing.
9.1.22 Centrifuge the suspension at 3500 x g5 with the brake off, for 30 minutes at 4°C.
Note: A higher x g is preferred as long as the speed is within the tube specifications.
9.1.23 Carefully discard 22 mL of supernatant without disturbing/dislodging the pellet.
Resuspend the pellet by vortexing in the remaining volume.
9.1.24 Use a 0.5 mL aliquot for DNA extraction using bead-beating, as described in Section 9.2.
20 December 2012
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Detection of Bacillus anthracis in Environmental Samples
9.2 DNA Extraction and Purification
9.2.1 Using the 8 cap strips, transfer one level capful (~50 mg) of the 106 (im glass beads and
one level capful (-50 mg) of the 425 - 600 (im glass beads (using a clean strip of caps
between bead sizes) into each gasketed, capped bead-beating tube.
9.2.2 In the BSC, pipet 0.5 mL of the suspension (Section 9.1.23) into pre-labeled, gasketed,
capped bead-beating 2 mL tube containing glass beads. Replace cap on tube securely.
Wipe outside of tube with bleach wipe.
9.2.3 Insert tube in tube holder of the bead-beater set at 4800 rpm for 3 minutes (180 seconds).
Instrument settings: Speed = 48; Time = 18. Press start. Bead-beating disrupts the cells
and spores to release the DNA.
9.2.4 Remove tube from bead-beater (tube will be warm), place in a cold block for 2 minutes
(or until cool to touch). If tube leaks during bead-beating, wipe tube and bead-beater
thoroughly with bleach wipe.
9.2.5 Supernatant separation and transfer
• Set up tubes; label one, 1.5 mL microcentrifuge tube, one yellow-top filter unit, two blue
Microcon® filter inserts and five blue Microcon® collection tubes with sample ID.
• In BSC, centrifuge the screw capped tube containing sample at 7000 rpm for 1 minute in
a microcentrifuge to pellet beads and particulate matter.
• Using a micropipettor, carefully transfer supernatant to yellow top filter collection tube
(try to avoid beads and particulate matter at bottom of tube).
• Centrifuge at 7000 rpm for 4 minutes.
• Open tube; remove the yellow top filter with sterile disposable forceps, gripping only on
the sides. Transfer filtrate to blue Microcon® filter insert. Do not transfer any particulate
matter that may be evident at bottom of tube. Replace filter and cap tube.
• Centrifuge at 7000 rpm for 1 minute.
• Remove the blue Microcon® filter insert with disposable forceps (gripping only the sides)
and transfer to a new collection tube.
9.2.6 First wash
• Add 400 nL of IX TE buffer to the filter.
• Centrifuge at 7000 rpm for 2 minutes.
• Carefully remove retentate from the top of the blue Microcon® filter insert, avoiding any
particulate matter visible on filter surface (tilt the tube for better viewing) and transfer
liquid into a new blue Microcon® filter insert and collection tube.
9.2.7 Second wash
• Add 400 jiL IX TE buffer to the filter.
• Centrifuge at 7000 rpm for 2 minutes.
• Transfer blue Microcon® filter insert with disposable forceps (gripping only the sides) to
a new collection tube.
21 December 2012
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Detection of Bacillus anthracis in Environmental Samples
9.2.8 Third wash
• Add 400 jiL IX TE buffer to the filter.
• Centrifuge at 7000 rpm for 2 minutes.
• Transfer blue Microcon® filter insert with disposable forceps (gripping only the sides) to
a new collection tube.
9.2.9 Fourth wash
• Add 400 (iL PCR-grade water to the filter.
• Centrifuge at 7000 rpm for 1 minute.
• Check fluid level in blue Microcon® filter insert. If above 200 uL, pulse spin for about
10 seconds (or less) until about 100 \\L of fluid is retained on top of white base.
9.2.10 Sample retrieval from the filter unit
• Use a micropipettor to carefully remove all of the retentate from the blue Microcon® filter
insert and transfer into clean, labeled 1.5 mL microcentrifuge tube. Avoid any particulate
matter.
• If there is less than 100 (iL of extract, transfer extract back to the same blue Microcon®
filter insert and add 100 \\L PCR-grade water and pulse spin to obtain about 100 \\L on
filter. Transfer retentate into clean, labeled 1.5 mL microcentrifuge tube.
• Using clean gloves, place tubes containing filter extracts in DNA loading station/hood in
preparation for PCR analyses (Section 9.3).
9.3 Real-time PCR Analyses
As compared to traditional PCR, real-time PCR uses a sequence-specific hybridization probe
sequence internal to the amplification primers, in addition to two target gene-specific amplification
primers. The probe is fluorescently labeled at the 5' end with a reporter dye/fluorophore and at the
3' end with a quencher dye (usually, Black Hole Quenchers). The emission of light/fluorescence
by the reporter dye is normally quenched by virtue of its proximity to the quencher dye. At the
annealing step in a PCR, along with the amplification primers, depending upon its orientation, the
probe sequence also hybridizes to its target site on the DNA strand downstream from the binding
site of one of the primers. During the enzymatic extension step when the probe comes in the way
of Taq DNA polymerase enzyme, the 5' exonuclease activity of the enzyme hydrolyzes the probe
sequence by cleaving individual nucleotides from the 5' end. Cleavage of the probe releases the
reporter dye from the proximal quencher allowing emission of measurable fluorescence.
Therefore, this assay is also known as the 5' exonuclease assay as it relies on the 5' to 3'
exonuclease activity of the Taq DNA polymerase enzyme to hydrolyze the probe. Thus, the PCR
amplification of a specific gene sequence can be detected by monitoring the increase in
fluorescence (Figure 1).
22 December 2012
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Detection of Bacillus anthracis in Environmental Samples
1) Reaction Mtaui e
Target ckDNA
Quenched
TaqMan' Probe
3) Anneal Primer; nud Probe
-
,, .1...T TTT 1 1.
\
4) Extension, Hydroh -sis,
and Detection
Polymerase
Figure 1. PCR Amplification.
As the amplification reaction proceeds, more amplicons become available for probe binding and
hydrolysis, and consequently, the fluorescence signal intensity per cycle increases. The increase in
fluorescence can be detected in real time on PCRthermocyclers. When the fluorescence level
crosses a set threshold value at a certain cycle number during the PCR, the result indicates the
presence of the target gene sequence in the DNA in the sample, which in turn indicates the
presence of a target pathogen in the sample. The PCR can specifically amplify a single copy of
target gene sequence and generate millions of copies in a matter of minutes.
The TaqMan® fluorogenic probe hydrolysis-based real-time PCR assays are commonly used in
biodetection. Using established computer software (e.g., Primer Express) and genome sequence
databases, bioagent-specific primers and probe nucleotide sequences for these assays are selected
in such a way that they are present only in a specific location on the unique gene and/or virulence
factor gene of interest for the detection and identification of a specific pathogen. These primers
and probe sequences are absent in any other gene of that pathogen or in the genes of any near
neighbor organisms. The primers generate a PCR product (amplicon) of a definite length/size.
For a high-confidence identification of pathogens, PCR assays for multiple pathogen-specific
genes are usually used. For example, for detection of B. anthracis, real-time PCR assays generally
target three separate genes. They include one gene each on pXOl and pXO2 plasmids (usually
targeting virulence genes) and one gene on the chromosome/genome. An algorithm based on the
positive detection of all three gene targets in a sample indicates the presence of virulent B.
anthracis spores. However, since this protocol is developed for the remediation phase of the
response where the B. anthracis strain has usually been identified and characterized, real-time
23 December 2012
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Detection of Bacillus anthracis in Environmental Samples
PCR using only the EPA-2 assay targeting the capsular antigen gene on the pXO2 plasmid is
recommended. Although, if needed, all three assays or any combination thereof can be performed
using the same sample DNA extract. Accordingly, the primers and probe sequences, and PCR
conditions for the two optional assays, EPA-1 (targeting the protective antigen gene on the pXOl
plasmid) and BC3 (targeting a hypothetical gene on the B. anthracis chromosome) are also
included.
The real-time PCR assays included in this protocol have been only partially characterized for
specificity, however, the use of these assays is currently recommended. These assays will be
replaced with fully characterized and validated assays upon availability.
Note: This procedure is to be carried out in an area designated for PCR only. A PCR-
workstation that is equipped with an ultraviolet (UV) light for sterilization must be used
for PCR Master Mix preparation. Micropipets and corresponding sterile, aerosol-
resistant pipet tips are used throughout this procedure for the addition of reagents.
Aseptic technique must be used throughout and all reagents must be kept at or near
4°C.
9.3.1 Decontaminate the PCR workstation by treating all work surfaces with a 10% pH
amended bleach solution, allowing the bleach to contact the work surface for a minimum
of 15 minutes prior to rinsing with sterile water. Turn on UV light for 15 minutes. After
decontamination, discard gloves and replace with a new clean pair.
Note: If gloves become contaminated, they should be disposed of and fresh gloves donned.
Only open one tube at a time throughout the process. At no point, should more than
one tube be open. Do not allow hands (gloved or otherwise) to pass over an open tube,
PCR plate, or any reagent container. All used pipet tips, gloves and tubes must be
discarded in a biohazard autoclave bag.
9.3.2 Determine the number of reactions that are to be run. Include four replicate reactions
each (for each assay) for a NTC, PC and three replicates of the PNC (blank) per run. In
addition, include three reactions for each sample and two reactions for the EIC for each
sample. Prepare a sufficient volume of Master Mix to allow for one extra reaction for
every ten reactions, so that there is enough Master Mix regardless of pipetting variations.
For example, if ten samples are to be analyzed a total of 61 reactions would be included
in the run [4-NTC, 4-PC, 3-PNC, 30-samples and20-EICs]. The amount of PCR Master
Mix prepared should be sufficient to run 70 reactions.
9.3.3 Based on the example provided above (i.e., 10 samples) the amount of Master Mix
required would be as indicated in Table 2.
Table 2. Example EPA-2 PCR Assay Master Mix Preparation for 70 Reactions
Reagent
TaqMan® 2X Universal Master Mix
Forward primer, 25 joM
Reverse primer, 25 joM
Probe, 2 uM
PCR-grade water
Total Volume
Volume
(HL)
12.5
0.3
0.3
1
5.9
20
Total
Volume (jiL)
875
21
21
70
413
1400
Final Concentration
(UM)
IX
0.3
0.3
0.08
N/A
24
December 2012
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Detection of Bacillus anthracis in Environmental Samples
Optional PCR Assays
If required the Master Mix for the optional assays should be prepared according to Table
3 based on the example provided in Section 9.3.2.
Table 3. Example EPA-1 and BC3 PCR Assay Master Mix Preparation for 70 Reactions
Note:
9.3.4
9.3.5
9.3.6
Note:
9.3.7
9.3.8
9.3.9
9.3.10
9.3.11
9.3.12
Reagent
TaqMan® 2X Universal Master Mix
Forward primer, 25 uM
Reverse primer, 25 uM
Probe, 2 uM
PCR-grade water
Total Volume
Volume
(HL)
12.5
1
1
1
4.5
20
Total
Volume (jiL)
875
70
70
70
315
1400
Final Concentration
(UM)
IX
1.0
1.0
0.08
N/A
The PC andNTC controls must be analyzed prior to sample analyses to verify that the
Master Mix works properly and is free of contamination.
In a clean PCR-preparation hood, pipet 20 (iL of Master Mix to four wells of the PCR
plate. Label two wells as NTC and two as PC.
Add 5 (iL of PCR-grade water into the NTC wells.
Cover the plate with edge seal and transfer the PCR plate to the BSC. Remove the seal
and add 5 (iL of the PC (B. anthracis DNA [10 pg/^L]) to the PC wells.
This step must be performed in the BSC outside the PCR clean room set-up area.
Change gloves.
Seal PCR plate with optical seal, using plate sealer for good contact. Change gloves.
Centrifuge sealed PCR plate for 1 minute at 2000 rpm and 4°C, using the PCR plate
safety cups or mini-plate centrifuge in the BSC.
Open the centrifuge safety cup and transfer PCR plate to the ABI 7500 Fast
thermocycler.
The PCR cycling conditions on the ABI 7500 Fast include an initial cycle of 50°C for 2
minutes, followed by one cycle of 95°C for 10 minutes, followed by 45 cycles of 95°C for
5 seconds, and 60°C for 20 seconds (use Fast Temperature Ramp rate: 3.5°C/s up and
3.5°C/s down). Fluorescence is automatically measured at the end of the 60°C annealing-
extension combined step.
If the Master Mix test results show "True Positive" assay detection for the PC and "True
Negative" assay detection for the NTC, then proceed with analyses of samples. If the
results are not "True" then repeat the PCR Master Mix preparation and testing protocol
and reanalyze.
In a clean PCR-preparation hood, pipet 20 (iL of Master Mix into the required number of
wells of a new PCR plate (as per the number of samples to be analyzed). An eight
channel micropipettor can be used to add the Master Mix to the plate. Label two wells as
NTC and two as PC. Label the rest of the wells such that there are five wells for each
sample (three wells for actual sample analyses and two wells for EICs for each sample).
9.3.13 Add 5 (iL of PCR-grade water into the NTC wells.
25
December 2012
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Detection of Bacillus anthracis in Environmental Samples
9.3.14 Cover the plate with edge seal and transfer the PCR plate to the BSC. Remove the seal
and add 5 (iL of the PC (B. anthracis DNA [10 pg/nL]) to the PC wells.
Note: This step must be performed in the BSC outside the PCR clean room set-up area.
Change gloves.
9.3.15 Add 5 (iL of the PNC extract to the three PNC wells.
9.3.16 Add 5 (iL of each sample DNA extract to the sample and EIC wells.
9.3.17 Add 1 jiL of the PC (B. anthracis DNA [50 pg/jiL]) to all the EIC wells.
Note: To minimize cross contamination the EICs should not be placed next to the field
samples when setting up the PCR tray.
9.3.18 Seal PCR plate with optical seal, using a plate sealer for good contact. Change gloves.
9.3.19 Centrifuge sealed PCR plate for one minute at 2000 rpm and 4°C, using the PCR plate
safety cups or mini-plate centrifuge in the BSC.
9.3.20 Transfer PCR plate to the ABI 7500 Fast thermocycler.
9.3.21 Run PCR using the thermocycling conditions as described in Section 9.3.10.
9.3.22 After completion of thermocycling, discard sealed PCR plate.
Note: PCR plates with amplified product should not be opened in the laboratory.
9.3.23 Laboratory clean-up procedures
• Dispose of all biological materials in autoclave bags (double bagged).
• Autoclave all waste materials at the end of the work day.
• Decontaminate counters and equipment with fresh bleach (Section 6.19), followed by
70% isopropyl and a DI water final rinse.
9.3.24 Refer to section 12.1 for Data Analyses and Calculations.
10.0 Post Decontamination Procedures for Rapid Viability-Polymerase Chain
Reaction (RV-PCR) Analyses
Acceptable sample types: Gauze wipes (2" x 2" 50% rayon/50% polyester), air filters (37 mm),
swabs (macrofoam), vacuum socks (large dust collection sample bags, 9 1/8" x 4", mean pore size
6.7 (im), vacuum filters (4" diameter filter), Sponge-Stick sampling tools, water and
decontamination waste water.
Note: Neutralization of decontamination agent(s) may be required prior to sample processing
and analyses.
10.1 RV-PCR
The RV-PCR method (Figures 2 and 3) is most useful for the analyses of samples collected during
and after decontamination because determination of the presence or absence of viable B. anthracis
spores (in the presence of a large number of dead spores) is a key analytical requirement during
this phase of the response. This method can be more sensitive than the traditional culture-based
method because almost all the spores recovered from the sample are used for analysis. It is
26 December 2012
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Detection of Bacillus anthracis in Environmental Samples
relatively rapid, cost-effective, less labor-intensive, less prone to inhibition by environmental
matrices, and less prone to interferences from the outgrowth of other bacteria, fungi, other
microbes and presence of other biological material in the sample. It also provides higher-
throughput and generates significantly less biohazardous and general laboratory wastes than the
culture-based method. Using the current version of the RV-PCR procedure a batch of 16 samples
can be analyzed in 15 hours. If the laboratory is running 7/24 approximately 150 samples can be
analyzed in 48 hours. If additional equipment and personnel are available, the throughput could be
increased.
The RV-PCR method is based on
a shift in PCR Ct value indicating
an increase in DMA, which is itself
due to an increase in cell number
due to organism viability
The method accurately
distinguishes live cells from dead
spores based on Ct0, Ctfinai and
ACt
ACt (Ct[T0] - Ct[T9]) > 9
ACt> 9 fora positive result
20 30
PCR Cycle
40
Figure 2. Example PCR Amplification Curves for the Initial T0 Aliquot and the Endpoint (Final)
Aliquot.
The RV-PCR method is a combination of culture and real-time PCR, a rapid, highly sensitive and
specific analytical method to detect and identify bioterrorism agents. Culturing the samples allows
the germination of viable B. anthracis spores recovered from processed samples. Real-time PCR
via a change in the CT value (Figure 2) offers a rapid determination of the viability and identity of
B. anthracis bacteria that grow from germinated spores in broth culture. Samples (air filter,
particulate [wipe, Sponge-Stick, swab, vacuum sock or filter], drinking water or decontamination
waste water) are processed in multiple spore extraction and wash steps. Recovered spores are
incubated in BHI broth for optimum growth of B. anthracis. After vortexing, an aliquot is
withdrawn for baseline analysis before incubating the broth culture in the filter cup at 36°C for 9
hours on a rotary shaker incubator. This is the T0 aliquot and is stored at 4°C for immediate
processing or at -20°C for an extended period until analysis. After the broth culture is incubated
for 9 hours, another aliquot is withdrawn. This is the T9 aliquot. Both the T0 and T9 aliquots are
then extracted and purified to obtain B. anthracis total DNA. The T0 and T9 DNA extracts are
then analyzed, in triplicate, using real-time PCR to detect the presence of B. anthracis DNA.
Figure 3 provides a flowchart for the RV-PCR analyses. The CT values for both the T0 and T9
DNA extracts are recorded and compared. A change in CT for the T9 aliquot relative to the CT for
the TO aliquot is calculated as follows: ACT (CT [T0] - CT [T9]). A ACT > 9 (i.e., the endpoint PCR
CT of < 36 for the T9 DNA extract in a 45-cycle PCR) is set as a cut-off value for a positive
detection of viable B. anthracis spores in the sample. The ACT > 9 criterion represents an
approximate three log increase in DNA concentration at T9 relative to T0. The increase in DNA
concentration at T9 is as a result of the presence of viable spores in the sample that germinated and
grew during the 9 hours of incubation in growth medium. Depending upon the end user's
requirement, sample complexity (dirtiness) and the phase of response during an event, a lower AQ
criterion of > 6 (a two log difference in DNA concentration) and a corresponding higher endpoint
27
December 2012
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Detection of Bacillus anthracis in Environmental Samples
PCR CT of < 39 could be set. The current protocol provides qualitative (presence or absence)
results. However, introduction of the Most Probable Number (MPN) technique in the RV-PCR
protocol (i.e., performing serial dilutions and replicate subsamples) could provide semi-
quantitative results.
Samples in
conical tube
with support
_L
Add extraction
buffer, vortex
Collect spores
by vacuum
filtration
Repeat
extraction step
and collect
spores
Wash with high
and low salt
buffers
Add growth
medium
Vortex, take T0
aliquot for PCR
Incubate at
37°C
Vortex, take L
aliquot for PCR
Sample Processing and Incubation
Ct[T0J
CtFJJ
ACt >9
Viable
spores
T0= Zero Hour Incubation I. = Final Incubation-Hours (Endpoint)
Figure 3. Flow Chart for RV-PCR Sample Analysis.
28
December 2012
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Detection of Bacillus anthracis in Environmental Samples
10.2 RV-PCR Sample Processing: Spore Recovery
Note: Gloves should be used and changed between samples and as indicated below.
10.2.1 Prior to sample processing, prepare the following items:
• Fill sample tube rack with 30 mL or 50 mL screw cap conical tubes and label as
appropriate.
• In a BSC, assemble manifold by connecting upper part (with 24 openings as 3 columns of
8 openings each) to lower part (with port) using six Allen screws. Place filter cups into
the manifold in the two outer columns (leaving the center column vacant). Verify that all
filter cups are completely pushed down in manifold such that the filter cup bottom is
touching the top surface of the manifold. Place a 50 mL tube cap (Section 5.2.6) on each
filter cup. Place blue pull-tab caps in a beaker (one for each filter cup with a couple extra)
and put inside a 37°C incubator (caps are easily to apply when pre-warmed).
• Vacuum: Prepare vacuum pump or house vacuum source; connect vacuum source to in-
line filter and to waste container filled with -150 mL of fresh undiluted bleach resulting
in a final concentration of approximately 10%, once filtration is complete (final waste
volume will be ~1.5 L).
Note: If using external vacuum pump, tape pump exhaust tube to BSC to vent exhaust inside
BSC.
• Capping tray set up: Add bottom caps to capping tray.
• For TO and T9 sample aliquots: In the BSC, for each sample 96-well tube rack or control,
set up the following tubes, each labeled with the sample ID, the time-point (T0 or T9), the
date, and the operator's initials:
- One 2 mL screw cap tube
- One 2 ml Eppendorf tube
- Two 1.5 mL Eppendorf tubes
Use a different tube rack (96-well tube rack in 8 x 12 format) for T0 and T9 tubes,
following the sample layout.
• Tape filter cup layout on outside glass window of the BSC.
• Special Instructions
- All procedures in the laboratory are to follow protocols that maintain a safe and clean
environment for the operators and reagents.
- All the procedures must be carried out in a BSC.
- Before and after sample analysis, decontaminate the BSC, pipet aids, centrifuge and
other equipment. Also, decontaminate all working areas suspected to be
contaminated.
- When operating in a BSC and throughout the laboratory, perform all steps of the
process using aseptic techniques. These precautionary techniques are to be used to
prevent contamination of equipment and individual reagents.
- Wear safety glasses, a lab coat, and gloves throughout the process.
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Detection of Bacillus anthracis in Environmental Samples
- If the gloves have somehow become contaminated, the gloves must be disposed of
and fresh gloves must be donned.
- Open one tube at a time throughout the process. At no point may more than one tube
be opened. Do not allow hands (gloved or otherwise) to pass over an open tube or
container.
- All used pipette tips, gloves, and tubes must be discarded in a biohazard autoclave
bag in the biosafety cabinet for later disposal after autoclaving.
10.2.2 Wipe and Air Filter Samples
Place mesh support over wipe or air filter samples in 30 mL tube by holding the wipe or
air filter to the side of the tube with sterile forceps and placing the coiled mesh support on
top (Section 9.1). Ensure the sample and mesh are in the bottom half of the tube
(avoiding the conical portion). Change gloves in between each sample. The support
keeps the wipe or air filter from interfering with pipetting activities and also improves
efficiency of spore extraction during vortexing. Proceed to Section 10.2.8.
10.2.3 Vacuum Samples (Socks and Filters)
For vacuum socks, using sterile scissors, cut top blue portion off and discard prior to
folding the sock from the top opening down. Make four, 1/2" folds in order to reduce the
sock size to about 1" x 2". Cut the sock five times above the 30 mL tube using scissors,
making sure to cut through all the folds. Place cut, folded sock in bottom half of tube
(avoiding conical portion) and using sterile forceps, place mesh support on top of sock
(Section 9.1). Bleach the BSC working surface and don a fresh pair of gloves in between
samples. Proceed to Section 10.2.8.
Note: The sampling processing procedure provided is for up to 1 tablespoon (~1 g of test
dust) of debris per sock sample. If socks received contain higher levels of debris,
follow procedure in Section 11.4.1.
For vacuum filters, ensure that the exposed filter surface (with debris) is facing up and
carefully cut through the evidence tape with a sterile scalpel in order to remove the top of
the cartridge. Using a pair of sterile forceps, transfer large pieces of debris into the
appropriate 30 mL tube, then fold filter in half with dirty, exposed filter side in, and then
fold in half again in order to fit it into the 30 mL tube. Place folded filter in bottom half
of tube (avoiding conical portion) and using two pairs of sterile forceps, place mesh
support on top of filter (Section 9.1). Proceed to Section 10.2.8.
10.2.4 Sponge-Stick Sampling Tools
• If the Sponge-Sticks/wipes are not in Stomacher® bags, aseptically transfer each sample
to a Stomacher® bag using sterile forceps. Change forceps between samples.
• Add 90 mL of PBST to each bag. Set Stomacher® (Section 5.5.28) to 260 rpm.
• Place a bag containing a sample into the Stomacher® (Section 5.5.28) so the Sponge-
Stick/wipe rests evenly between the homogenizer paddles and stomach each sample for 1
minute.
• Open the door of the Stomacher® (Section 5.5.28) and remove the bag. Grab the wipe
from the outside of the bag with hands. With the bag closed, move the Sponge-
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Detection of Bacillus anthracis in Environmental Samples
Stick/wipe to the top of the bag while using hands to squeeze excess liquid from the
Sponge-Stick/wipe.
• Open the bag, remove and discard the Sponge-Stick/wipe using sterile forceps.
• Repeat steps (Section 10.2.4) described above for each sample.
• Allow bags to sit for 10 minutes to allow elution suspension foam to settle.
• Process one stomacher bag sample at a time, transfer 20 mL at a time to the
corresponding filter cup (with vacuum set to 5 - 10 psi), allowing complete filtration
prior to the subsequent addition, until entire liquid volume has been processed. Use a
new 25 mL serological pipet for each transfer.
• Turn off vacuum pump.
• Add 20 mL of cold (4°C) extraction buffer without Tween® 80 to each filter cup, and
wait for 5 minutes prior to turning on the vacuum to 5 - 10 psi. Complete filtration
through the filter cups. Washing the filter with extraction buffer containing 30% ethanol
may reduce the number of vegetative cells that may compete with B. anthracis spore
outgrowth.
• Proceed to Section 10.3.
10.2.5 Swabs
Place swab into the 30 mL tube and cut handle with sterile scissors if necessary to fit into
the tube. Using sterile forceps, place the mesh support over the swab (Section 9.1).
Proceed to Section 10.2.8.
10.2.6 Water Samples (Large volume [10 L - 100 L], drinking water)
• Please see Appendix A for primary (Section 2.0) and secondary (Section 3.0)
concentration of large volume (10 L - 100 L) water samples. For water samples < 10 L,
please refer to Appendix A, Section 3.0, secondary concentration.
• After secondary water concentration, using a 25 mL serological pipette add 15 mL of
PBST buffer to the 50 mL conical tube with membrane filter (Appendix A, Section 3.5).
Repeat for each tube.
• Set vortexer (Section 5.5.16) to high intensity.
• Vortex membrane in 10 second bursts for 2 minutes to dislodge spores, taking care to
prevent the liquid from entering the tube cap. Repeat for each tube.
• Let tubes settle for 2 minutes.
• Using a new 25 mL serological pipette, transfer as much liquid as possible to the
corresponding filter cup while avoiding any settled particles during pipetting.
• Repeat for each sample tube.
• Turn on vacuum pump to 5 - 10 psi in order to collect spores onto filter cups.
• Repeat extraction of membrane filter by adding another 15 mL of PBST buffer to the 50
mL conical tube with membrane and vortex for 2 minutes with 10 second bursts, as
described above.
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Detection of Bacillus anthracis in Environmental Samples
• After 2 minute settling, transfer as much liquid as possible to the corresponding filter cup
using a 25 mL serological pipet while avoiding any settled particle.
• Complete filtration of liquid through filter cups. Turn off the vacuum pump.
• Add 20 mL of cold (4°C) extraction buffer without Tween® 80 to each filter cup, and
wait for 5 minutes prior to turning on the vacuum to 5 - 10 psi. Complete filtration
through the filter cups. Washing the filter with extraction buffer containing 30% ethanol
may reduce the number of vegetative cells that may compete with B. anthracis spore
outgrowth.
• Proceed to Section 10.3.
10.2.7 Water Samples (small volume [< 50 mL], surface or drinking water)
• Place manifold and filter cups in BSC. Label all filter cups, following the sample tube
rack layout. Document filter cup and sample tube labels.
• Turn on vacuum pump to 5 - 10 psi.
• Mix water sample by vortexing 5-10 seconds, then using a 25 mL serological pipet
transfer 20 mL of water to the corresponding filter cup.
• Dispose of pipet in waste container. Perform second transfer of 20 mL to same filter cup
using a new serological pipet.
Note: Additional 20 mL transfers may be conducted.
• Cap sample tube. Change gloves.
• After performing transfers to the corresponding filter cup for each water sample, check
that all sample tube caps are secure. Place tube rack in plastic bag, seal and bleach bag.
• Store water sample tubes at 4°C as an archive until analyses are completed or until
directed to discard samples.
• Turn off the vacuum pump.
• Add 20 mL of cold (4°C) extraction buffer without Tween® 80 to each filter cup, and
wait for 5 minutes prior to turning on the vacuum to 5 - 10 psi. Complete filtration
through the filter cups. Washing the filter with extraction buffer containing 30% ethanol
may reduce the number of vegetative cells that may compete with B. anthracis spore
outgrowth.
• Proceed to Section 10.3.
10.2.8 Place manifold and filter cups with 50 mL tube caps in BSC. Label all filter cups,
following the sample tube rack layout. Document filter cup and sample tube labels.
10.2.9 Add 20 mL of cold (4°C) extraction buffer with Tween® 80 to samples (use 5 mL for
swabs) placed in 30 mL conical tubes (50 mL conical tubes for Sponge-Stick samples) in
tube rack (up to 16 tubes per rack). Use a new serological pipet to transfer buffer from a
sterile, 250 mL screw capped bottle to each tube (keep bottle cap loosely over opening
between transfers). Uncap one tube at a time, add extraction buffer, close tube and place
it back in tube rack. Check that all caps are on tubes securely. Label tubes as appropriate
and document location in rack.
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Detection of Bacillus anthracis in Environmental Samples
10.2.10 Place tube rack in plastic bag, seal, double bag and bleach the bag prior to transferring to
the platform vortexer located outside the BSC.
10.2.11 Vortex samples for 20 minutes on platform vortexer (Section 5.5.15), with the speed set
to 7.
10.2.12 After vortexing, transfer sample tube rack to the BSC. Remove tube rack from plastic
bag and discard the bag.
10.2.13 Vortex up to 8 sample tubes on a single-tube vortexer (Section 5.5.16) in the BSC, for 3 -
5 seconds each. Let sit for at least 2 minutes to allow large particles to settle prior to
aliquoting (for samples containing debris). If required, allow the tubes to settle up to 5
minutes.
10.2.14 Uncap tube one at a time. Using a 25 mL serological pipet (10 mL pipet for swabs)
carefully transfer 13 mL (5 mL for swabs) to corresponding filter cup by lifting 50 mL
tube cap slightly (same position in the tube rack as in filter cup manifold). Dispose of
pipet in waste container. Cap sample tube and place tube back in rack. Change gloves.
Turn on vacuum pump at 5 - 10 psi.
10.2.15 Repeat Section 10.2.14 for each sample tube using a new serological pipet for each
sample, processing one sample at a time and up to 8 samples as a set, not exceeding 2 sets
of 8 (16 sample) per manifold (in rows 1 and 3). Repeat Section 10.2.13 for second set of
up to 8 sample tubes.
10.2.16 Complete filtration of liquid through filter cups. Change gloves.
10.2.17 Perform the second spore extraction. Uncap one sample tube at a time.
10.2.18 Add 20 mL (5 mL for swabs) of cold (4°C) extraction buffer without Tween® 80 to each
sample tube, one at a time with a new 25 mL serological pipet for each sample. Keep the
buffer bottle loosely covered between transfers. Recap the sample tube after each buffer
addition.
10.2.19 After adding extraction buffer to all of the tubes, check that all caps are tight. Place rack
in plastic bag, seal and bleach the bag. Transfer bagged tube rack to platform vortexer
(Section 5.5.15) located outside the BSC.
10.2.20 Vortex rack for only 10 minutes, with speed set to 7.
10.2.21 Repeat sections 10.2.12 - 10.2.16 except transfer 15-16 mL to the corresponding filter
cup instead of 13 mL, taking care to avoid settled particles during aliquoting. Proceed to
RV-PCR processing section (Section 10.3) below, with filter cup manifold.
10.2.22 Check that all caps are on sample tubes securely. Place tube rack in a plastic bag, seal
and bleach the bag. Store the samples at 4°C as an archive until analyses are completed
or until directed to discard samples.
10.3 RV-PCR Sample Processing: Buffer Washes and Broth Culture
10.3.1 Place into a 37°C incubator: Blue filter cup caps, one for each filter cup, in a ziplock
bag.
Note: Caps are easier to place on filter cups when pre-warmed.
10.3.2 Place into BSC: 25 mL and 10 mL (for swab samples) serological pipets and cold (4°C)
high salt wash buffer (pH 6.0) in 250 mL screw cap bottle.
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Detection of Bacillus anthracis in Environmental Samples
10.3.3 To each filter cup, transfer 20 mL (10 mL for swab samples) of cold (4°C) high salt wash
buffer (pH 6.0) using a 25 mL serological pipet (10 mL pipet for swabs) and lifting 50
mL tube cap slightly, keeping the bottle covered between transfers. Use new pipet for
each filter cup. Complete filtration of liquid through the filter cups. Change gloves.
10.3.4 Place into the BSC: 10 mL serological pipets and cold (4°C) IX low salt wash buffer, pH
7.4, in 250 mL screw cap bottle.
10.3.5 Transfer 20 mL of cold (4°C) IX low salt wash buffer (pH 7.4) to each filter-cup using a
25 mL serological pipet (by lifting 50 mL tube cap slightly). Keep the bottle covered
between transfers and use new pipet for each filter cup.
10.3.6 Complete filtration of liquid through filter cups. Remove 50 mL tube caps and dispose to
waste. Turn off vacuum pump. Change gloves.
10.3.7 Unscrew the manifold top using an Allen wrench. Break the seal on manifold to ensure
there is no vacuum by inserting a plate sealer between manifold top and bottom. Using
gloves hold the sides of the filter cup manifold top and remove it from the bottom
vacuum manifold and place on top of the capping tray, fitted with bottom caps (Section
10.2.1). Press down firmly to ensure caps are securely fastened to filter cup bottom ports.
Place bleach wipes over the manifold bottom until it can be disinfected. Change gloves.
10.3.8 Place into the BSC: 5 mL serological pipets, 200 \\L pipettor, 200 \\L tips, cold (4°C)
BHI broth aliquoted in 50 mL conical tubes, sharps container and blue filter cup caps
(pre-warmed in 37°C ± 1°C incubator).
10.3.9 Pipet 3.5 mL of cold BHI broth into each filter cup using a 5 mL serological pipet. Use a
new pipet for each filter cup.
10.3.10 Firmly press blue caps onto filter cups prior to vortexing. Record the time of the BHI
broth addition since this represents T0.
10.3.11 Place the capped filter cup manifold in a plastic bag, seal, double bag and bleach the bag.
10.3.12 Vortex the filter cups for 10 minutes on the platform vortexer (Section 5.5.15), setting 7.
10.3.13 Place 2 mL screw cap tubes for T0 aliquots into the cold block in the BSC.
10.3.14 After vortexing, transfer filter cup manifold in capping tray to the BSC. Remove bag.
10.3.15 Uncap one filter cup at a time and open the corresponding 2 mL tube. Using a 1 mL
pipettor while gently pipetting up and down 10 or more times to mix the sample (and to
avoid aerosol generation), transfer 1 mL (T0 aliquot) from each cup to the corresponding
pre-chilled (cold block) 2 mL tube. Cap the tube and place it back into the cold block.
10.3.16 Repeat Section 10.3.15 for each filter cup.
10.3.17 After transferring the T0 aliquot for all of the samples, place the capped filter cup
manifold in a plastic bag, seal, double bag and bleach the outer bag.
10.3.18 Transfer bagged filter cup manifold in capping tray to the shaker incubator. Secure the
manifold using manifold rack or pins (for single manifold). Incubate at 37°C ± 1°C at
230 rpm, for 9 hours (i.e., 9 hours from the addition of BHI broth to the filter cups).
10.3.19 Process 1 mL T0 aliquots in 2 mL screw cap tubes using the Manual DNA Extraction and
Purification Protocol (starting from Section 10.4.9), below.
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Detection of Bacillus anthracis in Environmental Samples
10.4 Manual DNA Extraction and Purification
Prepare lysis buffer with anti-foam according to manufacturer's instructions in the Magnesil
Blood Genomic, Max Yield System, Kit. Prepare the alcohol wash solution by adding ethanol and
isopropyl alcohol according to manufacturer's instructions. Transfer sufficient volume of buffer
to sterile, 100 mL reservoir immediately before use. Pre-heat heat block to 80°Cprior to Section
10.4.8.
Note: 1 mL T0 and T9 aliquots are processed in the same manner, as described below.
10.4.1 The TO aliquots can be extracted and purified during incubation of the T9 aliquots.
10.4.2 After the 9 hour incubation, remove the filter cup manifold from the shaker incubator.
10.4.3 Vortex filter cups for 10 minutes on platform vortexer (Section 5.5.15) with speed set to
7.
10.4.4 Transfer the filter cup manifold to the BSC, remove and discard bags.
10.4.5 Set up 2 mL screw cap tubes for T9 aliquots in a 96-well tube rack (8 x 12) and verify
that 2 mL tube labels match the filter cup layout. Maintain the tube layout when
transferring tubes between the magnetic stand and the 96-well tube rack. Do not use 1.5
mL tubes. Transfer T9 aliquot screw cap tubes to the BSC.
10.4.6 Uncap one filter cup at a time and open the corresponding 2 mL tube. Using a 1 mL
pipettor, swirl pipet tip gently in filter cup, while gently pipetting up and down 10 or
more times to mix sample (and to avoid aerosol generation), transfer 1 mL (T9 aliquot)
from each cup, and transfer to corresponding T9 aliquot tube in the 96-well tube rack; cap
the tubes.
10.4.7 Repeat Section 10.4.6 for each filter cup.
10.4.8 Centrifuge 2 mL screw cap tubes at 14,000 rpm for 10 minutes (4°C). Remove 800 (iL of
the supernatant from each tube, using a 1000 (iL pipettor and dispose to waste. Do not
disturb the pellet (use a new tip for each sample and discard tips in a sharps container). If
processing for DNA extraction immediately, proceed to Section 10.4.11.
10.4.9 Store T9 aliquots at -20°C until further processing, if the remaining steps of the protocol
cannot be conducted immediately.
Note: T0 and T9 extractions can be completed separately.
10.4.10 Thaw T0 and T9 aliquots if they were stored at -20°C.
10.4.11 Add 800 \\L of lysis buffer using a 1000 \\L pipettor with a new tip for each sample. Cap
the tubes and mix by vortexing on high (-1800 rpm) in 10 second pulses for a total of 60
seconds and place in 96-well tube rack at room temperature. Change gloves in between
the samples.
10.4.12 Vortex each screw-cap tube briefly (low speed, 5-10 seconds) and transfer the sample
volume to a 2 mL Eppendorf tube (ensure the tubes are labeled correctly during transfer).
Change gloves in between each sample. Incubate the T0 and T9 lysate tubes at room
temperature for 5 minutes.
10.4.13 Vortex the PMPs on high (-1800 rpm) for 30 - 60 seconds, or until they are uniformly
resuspended. Keep PMPs in suspension by briefly vortexing (3-5 seconds) before
adding to each T0 and T9 lysate tube.
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Detection of Bacillus anthracis in Environmental Samples
10.4.14 Uncap one tube at a time and add 600 (iL of PMPs to each T0 and T9 lysate (containing 1
mL sample), hereafter referred to as "T0 and T9 tubes" using a new pair of gloves for each
tube. Mix by briefly vortexing (use a new tip for each sample and discard used tips in a
sharps container). Change gloves in between each tube.
10.4.15 Repeat Section 10.4.14 for all T0 and T9 tubes, vortexing the PMPs suspension (10.4.13)
between each T0 and T9 tube.
10.4.16 Vortex each T0 and T9 tube for 5-10 seconds (high), incubate at room temperature for 5
minutes, briefly vortex, and then place on the magnetic stand with hinged-side of the tube
facing toward the magnet. After all the tubes are in the stand, invert tubes 180 degrees
(upside-down) turning away from you, then right side-up, then upside down toward you,
then right side-up (caps up) position. This step allows all PMPs to contact the magnet.
Check to see if any beads are in the caps and if so, repeat the tube inversion cycle again.
Let the tubes sit for 5 - 10 seconds before opening. Maintain the tube layout when
transferring tubes between the magnetic stand and the 96-well tube rack.
10.4.17 Uncap each tube, one at a time and withdraw all liquid using a 1000 \\L pipettor with the
pipet tip placed in the bottom of 2 mL tube, taking care not to disturb the PMPs. Ensure
that all the liquid is removed. Use a new pipet tip to remove any residual liquid, if
necessary. If liquid remains in the tube cap, remove by pipetting. Dispose tip and liquid
in a sharps container. Recap tube. Change gloves.
Note: Section 10.4.17 can be combined with Section 10.4.18. After withdrawing the liquid in
Section 10.4.17, add 360 [iL of Lysis buffer using a separate pipettor and new tip.
10.4.18 Uncap each T0 and T9tube, one at atime, and add 360 \\L of lysis buffer using a 1000 \\L
pipettor. Use a new tip for each sample and discard tips in a sharps container. Cap and
vortex on low setting for 5-10 seconds, and transfer to 96-well tube rack.
10.4.19 After adding lysis buffer to all of the T0 and T9 tubes, vortex each tube for 5-10 seconds
(low) and place back on the magnetic stand. After all tubes are in the stand, follow tube
inversion cycle, as described in Section 10.4.16.
10.4.20 Remove all the liquid as described in Section 10.4.17, except that a glove change
between samples is not required. Use a new tip for each T0 and T9 tube (discard used tips
in a sharps container). Recap the tube.
Note: Section 10.4.20 can be combined with Section 10.4.21. After withdrawing the liquid in
Section 10.4.20, add 360 [iL of Lysis buffer using a separate pipettor and new tip. If
the steps are combined, cap the tube after the buffer addition.
10.4.21 Repeat Sections 10.4.18 - 10.4.20 for all tubes.
Note: Section 10.4.21 can be combined with Section 10.4.22. After withdrawing the liquid in
Section 10.4.17, add 360 [iL of Salt Wash buffer using a separate pipettor and new tip.
If the steps are combined, cap the tube after the buffer addition.
10.4.22 1st Salt Wash: Uncap each T0 and T9 tube, one at a time, and add 360 \\L of Salt Wash
solution (VWR Cat. No. PAMD1401 or equivalent). Use a new tip for each T0 and T9
tube and discard used tips in a sharps container. Cap and transfer to 96-well tube rack.
10.4.23 After adding the Salt Wash solution to all of the T0 and T9 tubes, vortex each tube for 5 -
10 seconds (low) and place on the magnetic stand. After all tubes are in the stand, follow
tube inversion cycle, as described in Section 10.4.16.
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Detection of Bacillus anthracis in Environmental Samples
10.4.24 Remove liquid as described in Section 10.4.17, except that a glove change between T0
and T9 tubes is not required. Use a new tip for each T0 and T9 tube and discard used tips
in a sharps container. Recap the tube. Repeat for all T0 and T9 tubes.
Note: Section 10.4.24 can be combined with Section 10.4.25. After withdrawing the liquid in
Section 10.4.24, add 360 [iL of Salt Wash buffer using a separate pipettor and new tip.
If the steps are combined, cap the tube after the buffer addition.
10.4.25 2nd Salt Wash: Repeat Sections 10.4.22 - 10.4.24 for all T0 and T9 tubes.
Note: Section 10.4.25 can be combined with Section 10.4.26. After withdrawing the liquid in
Section 10.4.25, add 500 [tL of Alcohol Wash buffer using a separate pipettor and new
tip. If the steps are combined, cap the tube after the buffer addition.
10.4.26 1st Alcohol Wash: Uncap each T0 and T9 tube, one at a time, and add 500 \\L of alcohol
wash solution. Use a new tip for each sample and discard used tips in a sharps container.
Cap and transfer to 96-well tube rack.
10.4.27 After adding alcohol wash solution to all of the T0 and T9 tubes, vortex each tube for 5 -
10 seconds (low speed) and place on the magnetic stand. After all T0 and T9 tubes are in
the stand, follow the tube inversion cycle, as described in Section 10.4.16.
10.4.28 Remove liquid as described in Section 10.4.17, except that a glove change between T0
and T9 tubes is not required. Use a new tip for each T0 and T9 tube and discard used tips
in a sharps container. Recap the tube.
Note: Section 10.4.28 can be combined with Section 10.4.29. After withdrawing the liquid in
Section 10.4.28, add 500 [iL of Alcohol Wash buffer using a separate pipettor and new
tip. If the steps are combined, cap the tube after the buffer addition.
10.4.29 2nd Alcohol Wash: Repeat Sections 10.4.26 - 10.4.28 for all T0 and T9 tubes.
Note: Section 10.4.29 can be combined with Section 10.4.30. After withdrawing the liquid in
Section 10.4.29, add 500 [iL of Alcohol Wash buffer using a separate pipettor and new
tip. If the steps are combined, cap the tube after the buffer addition.
10.4.30 3rd Alcohol Wash: Repeat Sections 10.4.26 - 10.4.28 for all T0 and T9 tubes.
Note: Section 10.4.30 can be combined with Section 10.4.31. After withdrawing the liquid in
Section 10.4.30, add 500 [iL of 70% ethanol wash buffer using a separate pipettor and
new tip. If the steps are combined, cap the tube after the buffer addition.
10.4.31 4th Alcohol Wash: Repeat Sections 10.4.26 - 10.4.28 except use 70% ethanol wash
solution for all tubes. After the liquid is removed, recap the tube and transfer to the 96-
well tube rack.
10.4.32 Open all T0 and T9 tubes and air dry for 2 minutes.
10.4.33 Heat the open T0 and T9 tubes in the heat block at 80°C until the PMPs are dry (-20
minutes). Allow all the alcohol solution to evaporate since alcohol may interfere with
analysis.
10.4.34 DNA elution: While they are in the heating block add 300 \\L of elution buffer to each T0
and T9 tube, and close tube.
10.4.35 Vortex for 10 seconds and let the tubes sit in the heating block for 80 seconds.
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Detection of Bacillus anthracis in Environmental Samples
10.4.36 Briefly vortex the tubes (5-10 seconds) taking care to prevent the liquid from entering
the tube cap and let the tube sit in the heating block for 1 minute.
10.4.37 Repeat Section 10.4.36 four more times.
10.4.38 Remove the tubes from the heating block, place them in a 96-tube rack in the BSC, and
let them sit at room temperature for at least 5 minutes.
10.4.39 Briefly vortex each tube (5-10 seconds) on low speed and centrifuge at 2000 rpm at 4°C
for 1 minute. Place tube in 96-well tube rack.
10.4.40 Briefly vortex each tube and place on the magnetic stand for at least 30 seconds. Bring
the cold block to the BSC.
10.4.41 Collect liquid from each T0 or T9 tube with a micropipettor and transfer to a clean,
labeled, 1.5 mL tube (-170 (iL) on a cold block (check tube labels to ensure the correct
order). Use a new tip for each tube and discard tips in a sharps container. Visually verify
absence of PMP carryover during final transfer. If magnetic bead carryover occurred,
place 1.5 mL tube on magnet, collect liquid, and transfer to a clean, labeled, 1.5 mL tube
(ensure the tubes are labeled correctly during transfer).
10.4.42 Centrifuge tubes at 14,000 rpm at 4°C for 5 minutes to pellet any particles remaining
with the eluted DNA; carefully remove supernatant and transfer to a new 1.5 mL tube
using a new tip for each tube (ensure the tubes are labeled correctly during transfer).
10.4.43 Store T0 and T9 DNA extract tubes "referred to as T0 and T9 DNA extracts" at 4°C until
PCR analysis (use photo-tray to transport 1.5 mL tubes in a rack).
Note: If PCR cannot be performed within 24 hours, freeze DNA extracts at -20"C.
10.4.44 Laboratory Clean-up procedures
• Dispose of all biological materials in autoclave bags (double bagged).
• Autoclave all waste materials at the end of the work day.
• Decontaminate counters and equipment with fresh pH amended bleach (Section 6.19),
followed by 70% isopropyl and a DI water final rinse.
10.5 Real-time PCR Analysis of T0 and T9 DNA Extracts
For real-time PCR, follow Sections 9.3 - 9.3.16 with the following exceptions and changes:
• No EIC control is required for the samples.
• PCR Master Mix for 6 reactions per sample is required to accommodate the T0 and T9
DNA extracts.
• For each batch of samples, PCR Master Mix should be made for 4 PCs, 4 NTCs, 3 PNCs
and 6 DNA extracts per sample (3 for T0 and 3 for T9 DNA extracts).
10.5.1 TO DNA extracts: Label 1.5 mL tubes with the sample identifier and "10-fold dilution".
Add 90 (iL of PCR-grade water to the tubes.
10.5.2 Mix TO DNA extracts by vortexing (3-5 seconds), spin at 14,000 rpm for 2 minutes, and
transfer 10 |oL of supernatant to 1.5-mL Eppendorf tubes with 90 |oL of PCR-grade water,
maintaining the plate layout.
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Detection of Bacillus anthracis in Environmental Samples
Note: No centrifugation is required (Section 10.5.2) ifPCR analysis is conducted
immediately after DNA elution (Section 10.4.42).
10.5.3 Mix diluted T0 DNA extracts by vortexing (5 seconds at low speed), and transfer 5 joL
from the tubes to the PCR plate (with PCR Master Mix).
10.5.4 T9 DNA extracts: Label 1.5 mL tubes with the sample identifier and "10-fold dilution".
Add 90 (iL of PCR-grade water to the tubes.
10.5.5 Mix T9 DNA extracts by vortexing (3-5 seconds), spin at 14,000 rpm for 2 minutes, and
transfer 10 \\L of supernatant to 1.5-mL Eppendorf tubes with 90 \\L of PCR-grade water,
maintaining the plate layout.
Note: No centrifugation is required (Section 10.5.5) if PCR analysis is conducted
immediately after DNA elution (Section 10.4.42).
10.5.6 Mix diluted T9 DNA extracts by vortexing (5 seconds), and transfer 5 |oL from the tubes
to the PCR plate (with PCR Master Mix).
10.5.7 Seal PCR plate with optical seal, using a plate sealer to ensure good contact. Change
gloves.
10.5.8 Centrifuge sealed PCR plate for 1 minute at 2000 rpm and 4°C using the PCR plate
safety cups or mini-plate centrifuge in the BSC.
10.5.9 Open the centrifuge safety cup and transfer PCR plate to ABI thermocycler.
10.5.10 Transfer the PCR plates to the ABI 7500 Fast thermocycler.
10.5.11 Run PCR using the thermocycler conditions described in Section 9.3.10.
10.5.12 After the PCR run, discard sealed PCR plate.
Note: PCR plates with amplified product should not be opened in the laboratory.
10.5.13 Follow laboratory cleanup protocol provided in Section 10.4.44.
10.5.14 Refer to Section 12.2 for Data Analyses and Calculations.
11.0 Post Decontamination Procedures for Culture Analyses
Acceptable sample types: Gauze wipes (2" x 2", 50% rayon/50% polyester), air filters (37 mm),
swabs (macrofoam), vacuum socks (large dust collection sample bags, 9 1/8" x 4", mean pore size
6.7 (im), vacuum filters (4" diameter filter), Sponge-Stick sampling tools, drinking water and
decontamination waste water.
Note: Neutralization of decontamination agent(s) may be required prior to sample processing
and analyses.
39 December 2012
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Detection of Bacillus anthracis in Environmental Samples
11.1 Sample Processing and Plating for Sponge-Sticks and Wipes
Note: Sterile gloves should be used and changed between samples and as indicated below.
11.1.1 Dislodge spores from the sample (Sponge-Sticks and wipes)
Note: All subsequent procedures involving manipulation of Sponge-Sticks, wipes, or spore
suspensions must be carried out in a BSC using appropriate PPE (e.g., gloves, lab
coat).
• If the Sponge-Sticks/wipes are not in Stomacher® bags, aseptically transfer each sample
to a Stomacher® bag using sterile forceps. Change forceps between samples.
• Add 90 mL of phosphate buffered saline with Tween® 20 (PBST) to each bag. Set
Stomacher® (Section 5.5.28) to 260 rpm.
• Place a bag containing a sample into the Stomacher® (Section 5.5.28) so the Sponge-
Stick/wipe rests evenly between the homogenizer paddles and stomach each sample for 1
minute.
• Open the door of the Stomacher® (Section 5.5.28) and remove the bag. Grab the wipe
from the outside of the bag with hands. With the bag closed, move the Sponge-
Stick/wipe to the top of the bag while using hands to squeeze excess liquid from the
Sponge-Stick/wipe.
• Open the bag, remove and discard the Sponge-Stick/wipe using sterile forceps.
• Repeat steps (Section 11.1.1) described above for each sample.
• Allow bags to sit for 10 minutes to allow elution suspension foam to settle.
Note: For RV-PCR analysis, proceed to Section 10.2.4. Do not proceed to Section 11.1.2.
11.1.2 Concentrate elution suspension
• Gently mix the elution suspension in the Stomacher® bag up and down 3 times with a
sterile 50 mL pipet. Remove half of the suspension volume (~45 mL) and place it in a 50
mL screw capped centrifuge tube. Place the remaining suspension (-45 mL) into a
second 50 mL tube.
• Record suspension volumes on tubes and data sheet.
• Repeat steps above (Section 11.1.2) for each sample.
• Place 50 mL tubes into sealing centrifuge buckets and decontaminate centrifuge buckets
before removing them from the BSC.
• Centrifuge tubes at 3500 x g, with the brake off, for 15 minutes in a swinging bucket
rotor.
Note: A higher x g is preferred as long as the speed is within the tube specifications.
• Remove the supernatant from each tube with a 50 mL pipet and discard leaving
approximately 3 mL in each tube. The pellet may be easily disturbed and not visible, so
keep the pipet tip away from the tube bottom. Use a sterile 50 mL pipet for each sample.
• Set the vortexer (Section 5.5.16) to high intensity. Set the sonicator water bath to high.
40 December 2012
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Detection of Bacillus anthracis in Environmental Samples
• Vortex the tubes for 30 seconds and transfer the tubes to the sonicator bath and sonicate
for 30 seconds. Repeat the vortex and sonication cycles twice.
• Remove suspension from one tube with a sterile 5 mL pipet and combine it with the
suspension in the other tube from the same sample. Measure final volume of suspension
with 5 mL pipet and record the result on the tube and data sheet.
• Repeat vortexing and sonication steps for each sample.
Note: For real-time PCR analyses (for the site characterization phase) proceed to Sections
9.2 (DNA Extraction and Purification) and 9.3 (Real-time PCR analyses). For culture
analyses proceed to 11.1.3, below.
11.1.3 Serially dilute the spore elution suspension in PBST
• Vortex the elution suspension on high for 30 seconds.
a. Transfer 1 mL of the suspension from the 50 mL tube to a 15 mL containing 9 mL of
PBST. Recap the tube and vortex it on high for 30 seconds. This is the 10"1
suspension.
b. Open the cap of the 10"1 suspension and transfer 1 mL of this suspension into a new 15
mL tube containing 9 mL of PBST. Recap the tube and vortex on high for 30 seconds.
This is the 10"2 suspension.
c. The above results in 3 spore suspensions: the initial wipe elution suspension
(undiluted) and 2 serial dilutions of the suspension in PBST (10"1 and 10"2).
• Repeat steps (a) through (b) for each sample.
11.1.4 Culture spore suspensions on SBA
Note: Plating of 100 [iL results in an additional 1:10 dilution of each of the suspensions.
Each of the following will be conducted in triplicate, resulting in the evaluation of 9
spread plates per sample:
a. After vortexing tubes, pipet 0.1 mL of undiluted suspension onto surface of pre-dried
SBA plate (labeled 10'1).
b. After vortexing tubes, pipet 0.1 mL of 10"1 suspension onto surface of pre-dried SBA
plate (labeled 10"2).
c. After vortexing tubes, pipet 0.1 mL of 10"2 suspension onto surface of pre-dried SBA
plate (labeled 10'3).
• After pipetting the 3 spread plates for each dilution, use a sterile L-Shaped spreader to
distribute the inoculum over the surface of the medium by rotating the dish by hand or on
a turntable. Please ensure that inoculum is evenly distributed over the entire surface of
the plate. Repeat for the next 2 replicate plates.
• Allow inoculum to absorb into the medium completely.
11.1.5 Invert the plates and incubate them at 37°C ± 1°C for a maximum of 3 days. Plates
should be examined within 18-24 hours after starting the incubation and at 72 hours of
incubation. Count the number of colonies and record results. B. anthracis produces flat
or slightly convex, 2-5 mm colonies, with edges that are slightly irregular and have a
"ground glass" appearance. Comma-shaped projections may arise from the colony edge.
41 December 2012
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Detection of Bacillus anthracis in Environmental Samples
B. anthracis is not (3-Hemolytic. However, weak hemolysis may be seen under areas of
confluent growth in aging cultures and should not be confused with (3-hemolysis.
a. If the number of colonies is < 300/plate, record actual number.
b. If the number of colonies is > 300/plate, record as "too numerous to count" (TNTC).
c. If no target colonies are observed, record as "None detected" and proceed to
evaluation of growth on MicroFunnel™ plates (11.1.7).
A minimum of 3 typical colonies should be confirmed using real-time PCR (Section
11.6).
11.1.6 Capture spores on MicroFunnel™ filter membranes and culture on SBA
• Place 3, 0.45 (im (pore-size) MicroFunnel™ filter funnels (Section 5.4.4) on the vacuum
manifold and moisten membrane with 5 mL PBST. All filtering should be done with a
vacuum pressure < 20 mm Hg.
• With the vacuum valve closed (and vacuum pressure released), place 10 mL of PBST
into each filter cup. Add 1.0 mL of the undiluted elution suspension each to two
MicroFunnel™ cups and to the third cup add the remainder.
• Open the vacuum valve and filter the suspension. Close the valve and release the vacuum
pressure. Rinse the walls of each MicroFunnel™ cup with 10 mL of PBST and filter.
Open the valve and complete filtration.
• Squeeze the walls of the MicroFunnel™ cup gently and separate the walls from the base
holding the filter. Discard cup. Remove each membrane with sterile forceps and place it
grid-side up on a SBA plate. Make sure that the filter is in contact with the surface of the
agar. If an air pocket occurs under the filter, use the sterile forceps to lift the edge of the
filter to release the air pocket.
• Record the exact volume of the undiluted elution suspension filtered (1.0 mL) on each
plate.
• Repeat steps (Section 11.1.6) described above for each sample.
11.1.7 Invert and incubate SBA plates with membranes at 37°C ± 1°C for a maximum of 3 days.
Plates should be examined within 18-24 hours after starting the incubation and at 72
hours of incubation. Count the number of colonies and record results. Confirm 1-3
colonies using real-time PCR (Section 11.6).
11.2 Sample Processing and Plating for Swabs
11.2.1 Dislodge spores from swabs
Note: All subsequent procedures involving manipulation of swabs or spore suspensions must
be carried out in a BSC using appropriate PPE (e.g., gloves, lab coat).
• If the swabs are not in screw cap centrifuge tubes, transfer each swab to sterile, plastic 15
mL screw cap centrifuge tube using sterile forceps.
• If necessary, cut the handle of the swab to fit into the tube using sterile scissors. Use
sterile forceps and scissors for each sample.
Note: Flaming scissors with an alcohol lamp will not be sufficient to sterilize scissors in
between samples due to the presence of Bacillus spores in the samples.
42 December 2012
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Detection of Bacillus anthracis in Environmental Samples
• Add 5 mL of PB ST to each tube.
• Set vortexer (Section 5.5.16) to high intensity.
• Vortex swab in 10 second bursts for 2 minutes to dislodge spores from swab.
• Using sterile forceps, remove the swab from the 15 mL centrifuge tube. Use the forceps
to press the tip of the swab against the inside of the tube to remove extra liquid from the
foam tip before discarding the swab.
• Repeat vortexing steps for each swab sample.
Note: For real-time PCR analyses (for the site characterization phase) proceed to Section
9.1.19. For culture analyses proceed to 11.2.2, below.
11.2.2 Serially dilute the spore elution suspension in PBST
• Vortex the elution suspension on high for 30 seconds.
a. Transfer 1 mL of the suspension from the 50 mL tube to a 15 mL tube containing 9
mL of PBST. Recap the tube and vortex it on high for 30 seconds. This is the 10"1
suspension.
b. Open the cap of the 10"1 suspension and transfer 1 mL of this suspension into a new 15
mL tube containing 9 mL of PBST. Recap the tube and vortex on high for 30 seconds.
This is the 10"2 suspension.
c. The above results in 3 spore suspensions: the initial wipe elution suspension
(undiluted) and 2 serial dilutions of the suspension in PBST (lO^and 10"2).
• Repeat steps (a) through (b) for each sample.
11.2.3 Culture spore suspensions on SBA
Note: Plating of 100 [iL results in an additional 1:10 dilution of each of the suspensions.
Each of the following will be conducted in triplicate, resulting in the evaluation of 9
spread plates per sample:
a. After vortexing tubes, pipet 0.1 mL of undiluted suspension onto surface of pre-dried
SBA plate (10"1 mL of the original elution suspension).
b. After vortexing tubes, pipet 0.1 mL of 10"1 suspension onto surface of pre-dried SBA
plate (10~2 mL of the original elution suspension).
c. After vortexing tubes, pipet 0.1 mL of 10"2 suspension onto surface of pre-dried SBA
plate (10~3 mL of the original elution suspension).
• After pipetting the 3 spread plates for each dilution, use a sterile L-shaped spreader to
distribute inoculum over the surface of the medium by rotating the dish by hand or on a
turntable. Please ensure that inoculum is evenly distributed over entire surface of the
plate. Repeat for the next 2 dilutions.
• Allow inoculum to absorb into the medium completely.
11.2.4 Invert the plates and incubate them at 37°C ± 1°C for a maximum of 3 days. Plates
should be examined within 18 - 24 hours after starting the incubation and at 72 hours of
incubation. Count the number of colonies and record results. B. anthracis produces flat
or slightly convex, 2-5 mm colonies, with edges that are slightly irregular and have a
43 December 2012
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Detection of Bacillus anthracis in Environmental Samples
"ground glass" appearance. Comma-shaped projections may arise from the colony edge.
B. anthracis is not (3-Hemolytic. However, weak hemolysis may be seen under areas of
confluent growth in aging cultures and should not be confused with (3-hemolysis.
a. If the number of colonies is < 300/plate, record actual number.
b. If the number of colonies is > 300/plate, record as "too numerous to count" (TNTC).
c. If no target colonies are observed, record as "None detected" and proceed to
evaluation of growth on MicroFunnel™ plates (11.2.6).
A minimum of 3 typical colonies should be confirmed using real-time PCR (Section
11.6).
11.2.5 Capture spores on MicroFunnel™ filter membranes and culture on SBA
• Place 3, 0.45 (im (pore-size) MicroFunnel™ filter funnels (Section 5.4.4) on the vacuum
manifold and moisten membrane with 5 mL PBST. All filtering should be done with a
vacuum pressure < 20 mm Hg.
• With the vacuum valve closed (and vacuum pressure released), place 10 mL of PBST
into each filter cup. Add 1.0 mL of the undiluted elution suspension each to two
MicroFunnel™ cups and to the third cup add the remainder.
• Open the vacuum valve and filter the suspension. Close the valve and release the vacuum
pressure. Rinse the walls of each MicroFunnel™ cup with 10 mL of PBST and filter.
Open the valve and complete filtration.
• Squeeze the walls of the MicroFunnel™ cup gently and separate the walls from the base
holding the filter. Discard cup. Remove each membrane with sterile forceps and place it
grid-side up on a SBA plate. Make sure that the filter is in contact with the surface of the
agar. If an air pocket occurs under the filter, use the sterile forceps to lift the edge of the
filter to release the air pocket.
• Record the exact volume of the undiluted elution suspension filtered (1.0 mL) on each
plate.
• Repeat steps (Section 11.2.5) described above for each sample.
11.2.6 Invert and incubate SBA plates with membranes at 37°C ± 1°C for a maximum of 3 days.
Plates should be examined within 18 - 24 hours after starting the incubation and at 72
hours of incubation. Count the number of colonies and record results. Confirm 1-3
colonies using real-time PCR (Section 11.6).
11.3 Sample Processing and Plating for Air Filters
11.3.1 Dislodge spores from air filter
Note: All subsequent procedures involving manipulation of filters or spore suspensions must
be carried out in a BSC using appropriate PPE (e.g., gloves, lab coat).
• Add 5 mL of sterile PBST into a leak-proof, 50 mL conical tube containing an air filter,
and close tube.
• Set vortexer (Section 5.5.16) to high intensity.
• Vortex membrane in 10 second bursts for 2 minutes to dislodge spores.
44 December 2012
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Detection of Bacillus anthracis in Environmental Samples
• Using sterile forceps remove the air filter from the conical tube and discard.
• Repeat the vortexing steps for each air filter.
Note: For real-time PCR analyses (for the site characterization phase) proceed to Sections
9.2 (DNA Extraction and Purification) and 9.3 (Real-time PCR analyses). For culture
analyses proceed to 11.3.2, below.
11.3.2 Serially dilute the suspension in PBST
• Vortex the elution suspension on high for 30 seconds.
a. Transfer 1 mL of the suspension from the 50 mL tube to a 15 mL tube containing 9
mL of PBST. Recap the tube and vortex it on high for 30 seconds. This is the 10"1
suspension.
b. Open the cap of the 10"1 suspension and transfer 1 mL of this suspension into a new 15
mL tube containing 9 mL of PBST. Recap the tube and vortex on high for 30 seconds.
This is the 10"2 suspension.
c. Open cap of the 10"2 suspension and transfer 1 mL of this suspension into a new 15
mL tube containing 9 mL of PBST. Recap the PBST tube and vortex on high for 30
seconds. This is the 10"3 suspension.
d. The above results in 4 spore suspensions: the initial sock elution suspension
(undiluted) and three serial dilutions of the suspension in PBST (10"1, 10"2 and 10"3).
• Repeat steps (a) through (c) for each sample.
11.3.3 Culture spore suspensions on SBA
Note: Plating of 100 [iL results in an additional 1:10 dilution of each of the suspensions.
Each of the following will be conducted in triplicate, resulting in the evaluation of 12
spread plates per sample:
a. After vortexing tubes, pipet 0.1 mL of undiluted suspension onto surface of pre-dried
SBA plate (10"1 mL of the original elution suspension).
b. After vortexing tubes, pipet 0.1 mL of 10"1 suspension onto surface of pre-dried SBA
plate (10~2 mL of the original elution suspension).
c. After vortexing tubes, pipet 0.1 mL of 10"2 suspension onto surface of pre-dried SBA
plate (10~3 mL of the original elution suspension).
d. After vortexing tubes, pipet 0.1 mL of 10"3 suspension onto surface of pre-dried SBA
plate (10~4 mL of the original elution suspension).
• After pipetting the 3 spread plates for each dilution, use a sterile L-shaped spreader to
distribute inoculum over the surface of the medium by rotating the dish by hand or on a
turntable. Please ensure that inoculum is evenly distributed over entire surface of the
plate. Repeat for next 3 dilutions.
• Allow inoculum to absorb into the medium completely.
11.3.4 Invert the plates and incubate them at 37°C ± 1°C for a maximum of 3 days. Plates
should be examined within 18-24 hours after starting the incubation and at 72 hours of
incubation. Count the number of colonies and record results. B. anthracis produces flat
45 December 2012
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Detection of Bacillus anthracis in Environmental Samples
or slightly convex, 2-5 mm colonies, with edges that are slightly irregular and have a
"ground glass" appearance. Comma-shaped projections may arise from the colony edge.
B. anthracis is not (3-Hemolytic. However, weak hemolysis may be seen under areas of
confluent growth in aging cultures and should not be confused with (3-hemolysis.
a. If the number of colonies is < 300/plate, record actual number.
b. If the number of colonies is > 300/plate, record as "too numerous to count" (TNTC).
c. If no target colonies are observed, record as "None detected" and proceed to
evaluation of growth on MicroFunnel™ plates (11.3.6).
A minimum of 3 typical colonies should be confirmed using real-time PCR (Section
11.6).
11.3.5 Capture spores on MicroFunnel™ filter membranes and culture on SBA
• Place 3, 0.45 (im (pore-size) MicroFunnel™ filter funnels (Section 5.4.4) on the vacuum
manifold and moisten membrane with 5 mL PBST. All filtering should be done with a
vacuum pressure < 20 mm Hg.
• With the vacuum valve closed (and vacuum pressure released), place 10 mL of PBST
into each filter cup. Add 1.0 mL of the undiluted elution suspension each to two
MicroFunnel™ cups and to the third cup add the remainder.
• Open the vacuum valve and filter the suspension. Close the valve and release the vacuum
pressure. Rinse the walls of each MicroFunnel™ cup with 10 mL of PBST and filter.
Open the valve and complete filtration.
• Squeeze the walls of the MicroFunnel™ cup gently and separate the walls from the base
holding the filter. Discard cup. Remove each membrane with sterile forceps and place it
grid-side up on a SBA plate. Make sure that the filter is in contact with the surface of the
agar. If an air pocket occurs under the filter, use the sterile forceps to lift the edge of the
filter to release the air pocket.
• Record the exact volume of the undiluted elution suspension filtered (1.0 mL) on each
plate.
• Repeat steps (Section 11.3.5) described above for each sample.
11.3.6 Invert and incubate SBA plates with membranes at 37°C ± 1°C for a maximum of 3 days.
Plates should be examined within 18-24 hours after starting the incubation and at 72
hours of incubation. Count the number of colonies and record results. Confirm 1-3
colonies using real-time PCR (Section 11.6).
11.4 Sample Processing and Plating for Vacuum Socks and Filters
11.4.1 Dislodge spores from the vacuum socks and concentrate elution suspension
Note: All subsequent procedures involving manipulation of vacuum socks or spore
suspensions must be carried out in a BSC using appropriate PPE (e.g., gloves, lab
coat).
• Place 50 mL of PBST into sterile, leak-proof, wide-mouth screw cap plastic container.
• Remove the sock from the bag by holding onto the upper blue plastic material. Wet the
sock by dipping the lower 1" of the vacuum sock into the PBST in the container.
46 December 2012
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Detection of Bacillus anthracis in Environmental Samples
• While holding the sock over the container, cut lower edge of sock as close to the lower
edge seam as possible with disposable sterile scissors. Use sterile scissors for each
sample.
Note: Flaming scissors with an alcohol lamp will not be sufficient to sterilize scissors in
between samples due to the presence of Bacillus spores in the samples.
• Submerge the sock in the PBST so that the liquid is allowed to enter the opening and wet
the contents inside.
• When the liquid appears to have wet the sock beyond about 1" from the bottom, cut a 1"
vertical slit up the center from the bottom of the sock. Then cut horizontally from side to
side, about 1" from the bottom, allowing the two pieces to fall into the container with
PBST.
• Submerge the lower edge of the sock again to allow wetting of the contents inside. Again
cut a 1" vertical slit up the center and horizontally from side to side to allow two
additional sections to fall into the container with PBST.
• Continue to submerge and cut the sock until all of the white filter part of the sock is in
pieces in the jar.
• Discard the upper blue portion of the vacuum sock and change gloves.
• Tightly close the container, seal with parafilm, and place on a platform shaker/rotator
with lock bars. Agitate samples at 300 rpm for 30 minutes.
Note: If shaker/rotator is outside of the BSC, the containers should be enclosed in plastic
bags and a sealed biotransport carrier.
• Remove the biotransport carrier from the shaker and place it in the BSC. Allow settling
of samples for 1 minute, then transfer 30 mL of supernatant from each sample into
corresponding 50 mL sterile, screw cap, conical tubes.
• Discard the settled material.
• Place the conical tubes into sealing centrifuge buckets within the BSC. Transport to
centrifuge and place them in a swinging bucket rotor.
• Centrifuge the supernatant at 3500 x g, with the brake off, for 15 minutes.
Note: A higher x g is preferred as long as the speed is within the tube specifications.
• After centrifugation, move the sealed centrifuge buckets back to the BSC.
• Carefully pipet off 25 mL of the supernatant and resuspend the pellet in the remaining 5
mL by vortexing the 5 mL sample for 1 minute with 10 second bursts.
11.4.2 Dislodge spores from the vacuum filters and concentrate the elution suspension
• Place 50 mL of PBST into a sterile, leak-proof, wide-mouth screw cap plastic container.
• Ensure that the exposed filter surface (with debris) is facing up and carefully cut through
the evidence tape with a sterile scalpel in order to remove the top of the cartridge.
Using a pair of sterile forceps, transfer large pieces of debris into the appropriate screw
cap container.
47 December 2012
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Detection of Bacillus anthracis in Environmental Samples
• Fold the filter in half with dirty, exposed filter side in, and then fold in half again in order
to fit it into the screw cap plastic container.
• Place folded filter in screw cap plastic container.
• Submerge the filter in the PBST so that the liquid is allowed to wet the entire filter.
• Tightly close the container, seal with parafilm. Place on a platform shaker/rotator with
lock bars. Agitate samples at 300 rpm for 30 minutes.
Note: If the shaker/rotator is outside of the BSC, the containers should be enclosed in plastic
bags and a sealed biotransport carrier.
• Remove biotransport carrier from the shaker and place in the BSC. Allow settling of
samples for 1 minute, then transfer 30 mL of supernatant from each sample into
corresponding 50 mL sterile, screw cap, conical tubes.
• Discard the settled material.
• Place conical tubes into sealing centrifuge buckets within the BSC. Transport them to
centrifuge and place on swinging bucket rotor.
• Centrifuge the supernatant at 3500 x g, with the brake off, for 15 minutes.
Note: A higher x g is preferred as long as the speed is within the tube specifications.
• After centrifugation, move the sealed centrifuge buckets back to the BSC.
• Carefully pipet off 25 mL of the supernatant and resuspend the pellet in the remaining 5
mL by vortexing the 5 mL sample for 1 minute with 10 second bursts.
Note: For real-time PCR analyses (for the site characterization phase) proceed to Sections
9.2 (DNA Extraction and Purification) and 9.3 (Real-time PCR analyses). For culture
analyses proceed to 11.4.3, below.
11.4.3 Serially dilute the spore elution suspension in PBST
• Vortex the elution suspension on high for 30 seconds.
a. Transfer 1 mL of the suspension from the 50 mL tube to a 15 mL tube containing 9
mL of PBST. Recap the tube and vortex it on high for 30 seconds. This is the 10"1
suspension.
b. Open the cap of the 10"1 suspension and transfer 1 mL of this suspension into a new 15
mL tube containing 9 mL of PBST. Recap the tube and vortex on high for 30 seconds.
This is the 10"2 suspension.
c. Open cap of the 10"2 suspension and transfer 1 mL of this suspension into a new 15
mL tube containing 9 mL of PBST. Recap the PBST tube and vortex on high for 30
seconds. This is the 10"3 suspension.
d. Resulting in 4 spore suspensions: the initial sock elution suspension (undiluted) and
three serial dilutions of the suspension in PBST (10"1, 10"2 and 10"3).
• Repeat steps (a) through (c) for each sample.
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Detection of Bacillus anthracis in Environmental Samples
11.4.4 Culture spore suspensions on SBA
Note: Plating of 100 [iL results in an additional 1:10 dilution of each of the suspensions.
Each of the following will be conducted in triplicate, resulting in the evaluation of 12
spread plates per sample:
a. After vortexing tubes, pipet 0.1 mL of undiluted suspension onto surface of pre-dried
SBA plate (1CT1 mL of the original elution suspension).
b. After vortexing tubes, pipet 0.1 mL of 10"1 suspension onto surface of pre-dried SBA
plate (10~2 mL of the original elution suspension).
c. After vortexing tubes, pipet 0.1 mL of 10"2 suspension onto surface of pre-dried SBA
plate (10~3 mL of the original elution suspension).
d. After vortexing tubes, pipet 0.1 mL of 10"3 suspension onto surface of pre-dried SBA
plate (10~4 mL of the original elution suspension).
• After pipetting the 3 spread plates for each dilution, use a sterile L-shaped spreader to
distribute inoculum over the surface of the medium by rotating the dish by hand or on a
turntable. Please ensure that inoculum is evenly distributed over entire surface of the
plate. Repeat for next 3 dilutions.
• Allow inoculum to absorb into the medium completely.
11.4.5 Invert the plates and incubate at 37°C ± 1°C for a maximum of 3 days. Plates should be
examined within 18-24 hours after starting the incubation and at 72 hours of incubation.
Count the number of colonies and record results. B. anthracis produces flat or slightly
convex, 2-5 mm colonies, with edges that are slightly irregular and have a "ground
glass" appearance. Comma-shaped projections may arise from the colony edge. B.
anthracis is not |3-Hemolytic. However, weak hemolysis may be seen under areas of
confluent growth in aging cultures and should not be confused with |3-hemolysis.
a. If the number of colonies is < 300/plate, record actual number.
b. If the number of colonies is > 300/plate, record as "too numerous to count" (TNTC).
c. If no target colonies are observed, record as "None detected" and proceed to
evaluation of growth on MicroFunnel™ plates (11.4.7).
A minimum of 3 typical colonies should be confirmed using real-time PCR (Section
11.6).
11.4.6 Capture spores on MicroFunnel™ filter membranes and culture on SBA
• Place 3, 0.45 (im (pore-size) MicroFunnel™ filter funnels (Section 5.4.4) on the vacuum
manifold and moisten membrane with 5 mL PBST. All filtering should be done with a
vacuum pressure < 20 mm Hg.
• With the vacuum valve closed (and vacuum pressure released), place 10 mL of PBST
into each filter cup. Add 1.0 mL of the undiluted elution suspension each to two
MicroFunnel™ cups and to the third cup add the remainder.
• Open the vacuum valve and filter the suspension. Close the valve and release the vacuum
pressure. Rinse the walls of each MicroFunnel™ cup with 10 mL of PBST and filter.
Open the valve and complete filtration.
49 December 2012
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Detection of Bacillus anthracis in Environmental Samples
• Squeeze the walls of the MicroFunnel™ cup gently and separate the walls from the base
holding the filter. Discard cup. Remove each membrane with sterile forceps and place it
grid-side up on a SB A plate. Make sure that the filter is in contact with the surface of the
agar. If an air pocket occurs under the filter, use the sterile forceps to lift the edge of the
filter to release the air pocket.
• Record the exact volume of the undiluted elution suspension filtered (1.0 mL) on each
plate.
• Repeat steps (Section 11.4.6) described above for each sample.
11.4.7 Invert and incubate SBA plates with membranes at 37°C ± 1°C for a maximum of 3 days.
Plates should be examined within 18 - 24 hours after starting the incubation and at 72
hours of incubation. Count the number of colonies and record. Confirm 1-3 colonies
using real-time PCR (Section 11.6).
11.5 Sample Processing and Plating for Water Samples
Note: All water samples prior to 11.5.1 have been concentrated according to Appendix A
Sections 2.0 and 3.0 (large volume) or Section 3.0 (small volume).
11.5.1 Dislodge and elute spores from the MicroFunnel™ membrane (from secondary water
concentration, Appendix A, Section 3.0)
Note: All subsequent procedures involving manipulation of membranes or spore suspensions
must be carried out in a BSC using appropriate PPE (e.g., gloves, lab coat).
• Add 5 mL of sterile PBST into a screw cap, 50 mL conical tube containing a membrane
filter, and close tube.
• Set vortexer (Section 5.5.16) to high intensity.
• Vortex the membrane in 10 second bursts for 2 minutes to dislodge spores.
• Using sterile forceps remove membrane from conical tube and discard.
• Repeat the vortexing steps for each membrane.
Note: For real-time PCR analyses (for the site characterization phase) proceed to Sections
9.2 (DNA Extraction and Purification) and 9.3 (Real-time PCR analyses). For culture
analyses proceed to 11.5.2, below.
11.5.2 Serially dilute the suspension in PBST
• Vortex the elution suspension on high for 30 seconds.
a. Transfer 1 mL of the suspension from the 50 mL tube to a 15 mL tube containing 9
mL of PBST. Recap the tube and vortex it on high for 30 seconds. This is the 10"1
suspension.
b. Open the cap of the 10"1 suspension and transfer 1 mL of this suspension into a new 15
mL tube containing 9 mL of PBST. Recap the tube and vortex on high for 30 seconds.
This is the 10"2 suspension.
c. Open cap of the 10"2 suspension and transfer 1 mL of this suspension into a new 15
mL tube containing 9 mL of PBST. Recap the PBST tube and vortex on high for 30
seconds. This is the 10"3 suspension.
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Detection of Bacillus anthracis in Environmental Samples
d. The above results in 4 spore suspensions: the initial sock elution suspension
(straight/neat undiluted) and 3 serial dilutions of the suspension in PBST (1CT1, 10~2
and 10'3).
• Repeat steps (a) through (c) for each sample.
11.5.3 Culture spore suspensions on SB A
Note: Plating of 100 [iL results in an additional 1:10 dilution of each of the suspensions.
Each of the following will be conducted in triplicate, resulting in the evaluation of 12
spread plates per sample:
a. After vortexing tubes, pipet 0.1 mL of undiluted suspension onto surface of pre-dried
SB A plate (1CT1 mL of the original elution suspension).
b. After vortexing tubes, pipet 0.1 mL of 10"1 suspension onto surface of pre-dried SBA
plate (10~2 mL of the original elution suspension).
c. After vortexing tubes, pipet 0.1 mL of 10"2 suspension onto surface of pre-dried SBA
plate (10~3 mL of the original elution suspension).
d. After vortexing tubes, pipet 0.1 mL of 10"3 suspension onto surface of pre-dried SBA
plate (10~4 mL of the original elution suspension).
• After pipetting the 3 spread plates for each dilution, use a sterile L-shaped spreader to
distribute inoculum over the surface of the medium by rotating the dish by hand or on a
turntable. Please ensure that inoculum is evenly distributed over entire surface of the
plate. Repeat for next 3 dilutions.
• Allow inoculum to absorb into the medium completely.
11.5.4 Invert plates and incubate at 37°C ± 1°C for a maximum of 3 days. Plates should be
examined within 18-24 hours after starting the incubation and at 72 hours of incubation.
Count the number of colonies and record results. B. anthracis produces flat or slightly
convex, 2-5 mm colonies, with edges that are slightly irregular and have a "ground
glass" appearance. Comma-shaped projections may arise from the colony edge.
B. anthracis is not (3-Hemolytic. However, weak hemolysis may be seen under areas of
confluent growth in aging cultures and should not be confused with (3-hemolysis.
a. If the number of colonies is < 300/plate, record actual number.
b. If the number of colonies is > 300/plate, record as "too numerous to count" (TNTC).
c. If no target colonies are observed, record as "None detected" and proceed to
evaluation of growth on MicroFunnel™ plates (11.5.6).
A minimum of 3 typical colonies should be confirmed using real-time PCR (Section
11.6).
11.5.5 Capture spores on MicroFunnel™ filter membranes and culture on SBA
• Place 3, 0.45 (im (pore-size) MicroFunnel™ filter funnels (Section 5.4.4) on the vacuum
manifold and moisten membrane with 5 mL PBST. All filtering should be done with a
vacuum pressure < 20 mm Hg.
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Detection of Bacillus anthracis in Environmental Samples
• With the vacuum valve closed (and vacuum pressure released), place 10 mL of PBST
into each filter cup. Add 1.0 mL of the undiluted elution suspension each to two
MicroFunnel™ cups and to the third cup add the remainder.
• Open the vacuum valve and filter the suspension. Close the valve and release the vacuum
pressure. Rinse the walls of each MicroFunnel™ cup with 10 mL of PBST and filter.
Open the valve and complete filtration.
• Squeeze the walls of the MicroFunnel™ cup gently and separate the walls from the base
holding the filter. Discard cup. Remove each membrane with sterile forceps and place it
grid-side up on a SB A plate. Make sure that the filter is in contact with the surface of the
agar. If an air pocket occurs under the filter, use the sterile forceps to lift the edge of the
filter to release the air pocket.
• Record the exact volume of the undiluted elution suspension filtered (1.0 mL) on each
plate.
• Repeat steps (Section 11.5.5) described above for each sample.
11.5.6 Invert and incubate SBA plates with membranes at 37°C ± 1°C for a maximum of 3 days.
Plates should be examined within 18-24 hours after starting the incubation and at 72
hours of incubation. Count the number of colonies and record results. Confirm 1-3
colonies using real-time PCR (Section 11.6).
11.6 Confirmation of B. anthracis Colonies by Real-time PCR Analysis
11.6.1 Pipet 100 (iL of PCR-grade water into a 1.5 mL Eppendorf microcentrifuge tube (Section
5.2.13).
11.6.2 Use a disposable 1 \\L inoculating loop or pre-wetted swab to remove bacterial growth
from a typical B. anthracis colony grown on SBA.
Note: In some cases, it may be difficult to remove the bacterial growth with a loop. If this
happens, use a sterile applicator swab. Be sure topre-wet the swab with PCR-grade
water before removing the bacterial growth.
11.6.3 Insert the loop or swab into the tube containing the PCR-grade water and immerse the in
the liquid.
11.6.4 Gently spin the loop or swab in the liquid to remove and resuspend the bacterial growth
in the water. Press the tip of the swab against the tube to remove the liquid from the tip
prior to discarding.
11.6.5 Lysate preparation
• Cap the microcentrifuge tubes containing the bacterial suspension and briefly vortex.
• Place the capped tubes in a floating rack if using the water bath. Otherwise place the
capped tube in the heat block at 95°C - 98°C.
• Heat the sample for 5 minutes.
• Remove the tubes from the water bath or heat block and place it directly in a cold block.
Chill for a minimum of 2 minutes.
• Place the microcentrifuge tubes in the refrigerated microcentrifuge. Centrifuge at 12,000
rpm for 2 minutes.
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Detection of Bacillus anthracis in Environmental Samples
11.6.6 Filtration of lysate using 0.1 um centrifugal filter unit (Section 5.1.23)
• Remove top cap from the filtrate collection tube.
• Hold the filter unit vertical with the filter cup opening facing up. Pipet the supernatant
from each microcentrifuge tube into the corresponding filterate collection tube. Avoid
removing any visible pellet material.
• Replace top cap onto the filtrate collection tube. Balance the tubes prior to placing the
filter unit into the microcentrifuge fixed-angle rotor.
• Centrifuge the filter units for 2 minutes at 8000 rpm. Ensure all supernatant is collected
in the filtrate cups.
Note: If the supernatant has not passed completely through the filter, centrifuge for an
additional 2 minutes. Repeat as necessary until all the supernatant has passed through
thefilter.
• Remove top cap and discard the filtrate cup using sterile disposable forceps. Replace top
cap.
• The liquid in the filtrate collection tube is the lysate for real-time PCR analysis.
• Wipe the outside of the tube containing lysate with bleach.
• It is safe to remove lysates from the BSL-3 after filtration and disinfecting the outside of
the tube.
• Lysates must be stored in a cold block while preparing for the PCR analysis.
• If PCR analysis will not be completed the same day the lysates are prepared, aliquot and
freeze them at -20°C.
Note: DNA extracted by this procedure should not be stored for more than one week.
11.6.7 Use 5 \\L of the lysate as the DNA template to run the PCR analysis in triplicate.
11.6.8 For real-time PCR, follow Sections 9.3 - 9.3.23 with the following exceptions and
changes:
• No PNC and EIC controls are required for the samples.
• For each batch of sample colonies, PCR Master Mix should be made for 4 PCs, 4 NTCs
and 3 replicates for DNA extracts per colony.
11.6.9 Refer to Sections 12.1 and 12.3 for Data Analyses and Calculations.
12.0 Data Analysis and Calculations
12.1 Real-time PCR During the Site Characterization Phase
Calculate the average CT from the replicate reactions for each sample, PC and the EIC, where
applicable. The average CT < 40 for the sample indicates a positive result suggesting the presence
of B. anthracis spores in the sample. A minimum of two out of three replicates must show CT < 40
for a sample result to be considered positive. If only one out of three PCR replicates for any
sample gives CT < 40, the PCR analysis of the DNA extract for that sample must be repeated.
53 December 2012
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Detection of Bacillus anthracis in Environmental Samples
If the EIC for a sample results in a CT value (> 3) compared to the CT value for the positive
control, there may be matrix inhibition. If the corresponding sample is negative (CT > 40) for B.
anthracis, the sample should be diluted 1:10 and the PCR assay should be repeated for that sample
along with the EIC with diluted sample extract. Negative controls (NTCs) should not yield any
measurable CT values; if CT values are obtained check for potential for cross-contamination and
repeat analysis. In addition, field blank samples should not yield any measurable CT values. If CT
values are obtained as a result of a possible contamination or cross-contamination, depending upon
the CT value, a careful interpretation of the CT values for the sample DNA extracts must be done
for the final result or the PCR analyses must be repeated.
12.2 RV-PCR
Calculate an average CT from the replicate reactions for T0 and T9 DNA extracts of each sample.
Subtract the average CT of the T9 DNA extract from the average CT of the T0 DNA extract. If
there is no CT for the T0 DNA extract (i.e., the T0 is non-detect), use 45 (total number of PCR
cycles used) as the CT. The change (decrease) in the average CT value from T0 to T9 (ACT) > 9
indicates a positive result suggesting the presence of viable B. anthracis spores in the sample. If
an incubation time longer than 9 hours was used for the RV-PCR, instead of T9, appropriate Tx
(incubation time) should be used. However, (ACT) > 9 algorithm should still be used for a positive
result. Depending upon the end user's requirement, sample complexity (dirtiness) and the phase of
response during an event, a lower ACT criterion of > 6 (a two log difference in DNA
concentration) and a corresponding higher endpoint PCR CT of < 39 could be set. A minimum of
two out of three T0 PCR replicates must result in CT values < 44 (in a 45-cycle PCR) to calculate
the average CT. A minimum of two out of three T9 PCR replicates (or Tx for other incubation
time) must result in CT values < 36 to calculate the average CT for a sample result to be considered
positive. Negative controls (NTCs) should not yield any measurable CT values above the
background level. If CT values are obtained as a result of a possible contamination or cross-
contamination, prepare fresh PCR Master Mix and repeat analysis. In addition, field blank
samples should not yield any measurable CT values. If CT values are observed as a result of a
possible contamination or cross-contamination, a careful interpretation of the CT values for the
sample DNA extracts and field blanks must be done to determine if the data is considered valid or
if the PCR analyses must be repeated.
12.3 Culture
12.3.1 Serial dilution plating
Count the number of typical colonies on replicate culture plates and calculate the average
number of colonies per plate. Apply the following (a - c) when counting the colonies
and report results based on the number of confirmed colonies.
Media sterility checks should not exhibit growth. Growth should also not be present on
SBA plates from field blank samples. If growth is observed on plates, colony
morphology should be evaluated to determine if contamination is due to the target
organism and potential source of contamination. Samples should be reanalyzed if QC
plates are contaminated with B. anthracis.
a. If the number of colonies is < 250/plate, record actual number.
b. If the number of colonies is > 250/plate, record as "TNTC".
c. If no target colonies are observed, record as "None detected".
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Detection of Bacillus anthracis in Environmental Samples
To determine the number of spores per sample divide the total number of B. anthracis
colonies by the dilution factor plated, and multiply by the conversion factor for 1 mL, and
the total suspension volume. For example if 201 colonies were observed on the 10"1
dilution plate, and the total suspension volume was 5 mL, the number of colonies per
sample would be 100,500.
[(201/0.1) x 10] x 5 = 100,500 spores per sample
12.3.2 MicroFunnel™ filter plating
Count the number of typical colonies on each filter and record. Apply the following (a -
c) when counting the colonies and report results based on the number of confirmed
colonies.
Media sterility checks should not exhibit growth. Growth should also not be present on
SBA plates from field blank samples. If growth is observed on filters, colony
morphology should be evaluated to determine if contamination is due to the target
organism and potential source of contamination. Samples should be reanalyzed if QC
plates are contaminated with B. anthracis.
a. If the number of colonies is < 80/plate, record actual number.
b. If the number of colonies is > 80/plate, record as "TNTC".
c. If no target colonies are observed, record as "None detected".
To determine the number of spores per 5 mL sample using the 1 mL aliquot plates,
multiply the total number of B. anthracis colonies on each plate by 5 (total suspension
volume). For example if 60 colonies were observed on one of the 1.0 mL plates, and the
total suspension volume was 5 mL, the number of colonies per sample would be 300.
60 x 5 = 300 spores per sample
To determine the number of spores per 5 mL using the third plate (remainder of the
volume, [1.7 - 2.7 mL) multiply the total number of B. anthracis colonies by the ratio of
the total suspension volume (5 mL) to the actual volume plated. For example if 60
colonies were observed on the plate, the volume plated was 2.7 mL and the total
suspension volume was 5 mL, the number of colonies per sample would be 111.
60 x (5/2.7) = 111 spores per sample
12.3.3 Confirmation of Colonies by Real-time PCR
Presence of B. anthracis typical colonies on the culture plate indicates the presence of
viable B. anthracis spores or vegetative bacteria in the sample. A minimum of three
typical colonies should be confirmed using real-time PCR. The CT < 40 for the sample
indicates a positive result suggesting the presence of B. anthracis in the respective
sample. Report the results based on the number of confirmed colonies. Negative
controls (NTCs) should not yield any measurable CT values above the background level.
If CT values are obtained as a result of a possible contamination or cross-contamination,
prepare fresh PCR Master Mix and repeat the analysis.
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Detection of Bacillus anthracis in Environmental Samples
13.0 Method Performance
To be completed upon protocol verification and/or validation.
14.0 Pollution Prevention
14.1 The solutions and reagents used in this method pose little threat to the environment when recycled
and managed properly.
14.2 Solutions and reagents should be prepared in volumes consistent with laboratory use to minimize
the volume of expired materials to be discarded.
15.0 Waste Management
15.1 It is the laboratory's responsibility to comply with all federal, state, and local regulations
governing waste management, especially the biohazard and hazardous waste rules and land
disposal restrictions. Following these regulations protects the air, water and land by minimizing
and controlling all releases from fume hoods and bench operations. Compliance with all sewage
discharge permits and regulations is also required.
15.2 Samples, reference materials and equipment known or suspected to be contaminated with or to
contain viable B. anthracis must be decontaminated prior to disposal.
15.3 Large volume water filtrates should be decontaminated using bleach (10% final concentration) for
a minimum of 30 minutes prior to disposing to the sanitary sewer (e.g., pouring down the drain).
15.4 For further information on waste management, consult The Waste Management Manual for
Laboratory Personnel (Reference 16.6) and Less Is Better: Laboratory Chemical Management for
Waste Reduction (Reference 16.7), both authored by the American Chemical Society.
16.0 References
16.1 U.S. Department of Health and Human Services, Centers for Disease Control and Prevention and
National Institutes of Health. 2009. Biosafety in Microbiological and Biomedical Laboratories
(BMBL), 5th Edition, http://www.cdc.gov/biosafety/publications/bmbl5/index.htm
16.2 American Chemical Society (ACS). 2005. Reagent Chemicals: Specification and Procedures,
Oxford University Press (USA), New York.
16.3 British Drug Houses, Ltd. 1957. AnalaR Standards for Laboratory Chemicals. 5th Edition.
BDH Ltd., Poole, Dorset, U.K.
16.4 United States Pharmacopeia. 2005. United States Pharmacopeia and National Formulary 24.
United States Pharmacopeial Convention, Md.
16.5 Francy, D.S., Bushon, R.N., Brady, A.M., Bertke, E.E., Kephart, C.M., Likirdopulos, C.A.,
Mailot, B.E., Schaefer, F.W. Ill and Lindquist, H.D.A. 2009. "Performance of Traditional and
Molecular Methods for Detecting Biological Agents in Drinking Water." U.S. Department of the
Interior/U.S. Geological Survey. Scientific Investigations Report 2009-5097.
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Detection of Bacillus anthracis in Environmental Samples
16.6 American Chemical Society (ACS) 1990. The Waste Management Manual for Laboratory
Personnel. American Chemical Society Department of Government Relations and Science
Policy, Washington, DC.
16.7 American Chemical Society (ACS). 2002. Less Is Better: Laboratory Chemical Management for
Waste Reduction. American Chemical Society Taskforce on RCRA (Resource Conservation and
Recovery Act of 1976), Washington, DC.
http://portal.acs.org/portal/fileFetch/CAVPCP 012290/pdf/WPCP 012290.pdf
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Detection of Bacillus anthracis in Environmental Samples
Appendix A
Ultrafiltration (UF) for the Detection of Bioterrorism Threat (BT)
Agents in Potable Water Samples
Note: This protocol should not be misconstrued as a laboratory standard operating procedure (SOP)
that addresses all aspects of safety; the laboratory should adhere to their established safety
guidelines.
At a MINIMUM these procedures should be performed in a Biological Safety Level (BSL)-3
facility using BSL-3 practices. It is recommended that all sample manipulations be performed
within a Class II (or higher) biological safety cabinet (BSC).
1.0 Sample Preparation
Note: Water samples should be concentrated as soon as possible after collection and analyses should
be initiated immediately, if possible. However, if analyses cannot be accomplished
immediately, the concentrated sample may be stored at 2°C - 8°Cfor up to 24 hours.
1.1 Laboratory Supplies
1.1.1 Asahi Kasai Rexeed 25SX Dialyzers (Dial Medical Supply Cat. No. 25SX or equivalent)
1.1.2 Masterflex® L/S #36 silicon tubing (Cole Farmer® Cat. No. EW-96410-36 or equivalent)
Note: An alternative to the Masterflex* tubing is #36 BioPharm Silicone tubing (Cole Farmer9 Cat.
No. EW-96420-36).
1.1.3 Masterflex® L/S #24 silicon tubing (Cole Farmer® Cat. No. EW-96410-24 or equivalent)
1.1.4 Masterflex® tubing reducing connectors (Cole Farmer® Cat. No. EW-40610-08 or
equivalent)
1.1.5 3-prong extension clamp (Cole Farmer® Cat. No. EW-08021-36 or equivalent)
1.1.6 Ring stand (Fisher Cat. No. 14-670C or equivalent)
1.1.7 Clamp connector/holder (Cole Farmer® Cat. No. EW-08041-20 or equivalent)
1.1.8 Nalgene® Analytical Filter Unit, 0.45 (im (Fisher Scientific Cat. No. 09-740-2IB or
equivalent)
1.1.9 Heavy duty pinchcock, metal clamp (Cole Farmer® Cat. No. EW-08126-0302 or
equivalent)
1.1.10 GN-6 Metricel® Membrane Filters, 0.45 (im (VWR Cat. No. 28148-926 or equivalent)
1.1.11 Forceps, sterile, disposable (Cole Palmer® Cat. No. U06443-20 or equivalent)
1.1.12 Hose clamps (Cole Parmer®)
(a) Large: #10 and #12 white, plastic (Cat. No. EW-06832-10, EW-06832-12 or
equivalent)
(b) Medium size: #6 and #8 white, plastic (Cat. No. EW-06832-06, EW-06832-08 or
equivalent) or 7/32" to 5/8" stainless steel (Cat. No. EW-06403-11 or equivalent)
(c) Small: #4 white, plastic (Cat. No. EW-06832-04 or equivalent) or 7/32" to 5/8"
stainless steel (Cat. No. EW-06403-11 or equivalent)
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Detection of Bacillus anthracis in Environmental Samples
1.1.13 1 L heavy duty polypropylene vacuum bottle (Fisher Scientific Cat. No. 06-443A or
equivalent)
1.1.14 3 port filling/venting closure cap with tubing (Fisher Scientific Cat. No. 02-923-13Y or
equivalent)
1.1.15 Barbed reducing Y connector 1/4 x 3/8 (Cole Farmer® Cat. No. EW-30726-33 or
equivalent)
1.1.16 DIN adapters (filter connectors)
(a) Small connectors for 24 tubing (Molded Products Cat. No. MPC-855NS.250PP or
equivalent)
(b) Large connectors for 36 tubing (Molded Products Cat. No. MPC-855NS.375PP or
equivalent)
1.1.17 Blood Port Storage Cap (screw cap), polypropylene (Molded Products Cat. No. MPC-
40PP or equivalent)
1.1.18 Ice bucket and ice
1.1.19 Flow regulator (Keck) tubing clamps (Cole Farmer® Cat. No. A-06835-07 or equivalent)
1.1.20 Ziplock bags
1.1.21 Parafilm
1.1.22 Bleach Wipes (Dispatch® Cat. No. 69150 or equivalent)
1.1.23 Bottle, sterile, 100 mL
1.1.24 Tubes, sterile, 15 mL (Fisher Scientific Cat. No. 339650 or equivalent)
1.1.25 Bottle, 1-L sterile polypropylene (Thermo Scientific-Nalgene® Cat. No. 2105-0032 or
equivalent)
1.1.26 Filter flask, sterile, 500 mL, glass or polypropylene (Fisher Scientific Cat. No. FB-300-
500; 10-182-5OA; or equivalent).
1.1.27 10 mL plastic pipets, sterile, T.D. bacteriological (Fisher Scientific Cat. No. 13-678-12E
or equivalent)
1.1.28 50 mL plastic pipets, sterile, T.D. bacteriological (Fisher Scientific Cat. No. 13-678-14C
or equivalent)
1.1.29 Pliers
1.1.30 Graduated cylinder (1 L) or graduated beaker (1 L)
1.1.31 Syringe, 60 mL
1.1.32 #7 rubber stopper, 500 mL flask, with hole (Fisher Scientific Cat. No. 14-135L or
equivalent)
1.1.33 Collapsible containers, 10 L or 20 L (Cole Farmer® Cat. No. EW-06100-30 or EW-
06100-40)
1.1.34 Vacushield™ Vent Device (HEPA filter) (VWR Cat. No. 55095-006 or equivalent)
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Detection of Bacillus anthracis in Environmental Samples
1.2 Equipment
1.2.1 Masterflex® Console Drive (Cole Farmer® Cat. No. EW-07554-90 or equivalent)
1.2.2 Masterflex® EasyLoad II Pump Head (Cole Farmer® Cat. No. SI-77200-52 or equivalent)
1.2.3 Jiffy-Jack® apparatus positioner (Cole Farmer® Cat. No. A-08057-40 or equivalent)
1.2.4 BD Clay Adams™ Nutator Mixer (VWR Cat. No. 15172-203 or equivalent)
1.2.5 Biological safety cabinet (BSC) - Class II or Class III
1.2.6 Vortex mixer (Fisher Scientific Cat. No. 02-215-365 or equivalent)
1.3 Reagents
1.3.1 1000X (10%) Sodium Poly-Phosphate (NaPP): Add 10 g of NaPP per 100 mL of sterile
reagent-grade water in a sterile 100-mL bottle. Cap the bottle and shake vigorously by
hand for 1 minute to mix the solution. If the water is cold (e.g., from refrigerator), let the
solution dissolve for 2 hours at room temperature, mixing for Iminute approximately
every 15 minutes. If water is initially at room temperature, the NaPP should dissolve
within 30 minutes (mixing vigorously by hand every 15 minutes). If the NaPP is not
completely dissolved in the water, place the NaPP solution in a water bath at 50°C and
incubate for 2 hours. Continue incubating until the NaPP is completely in solution. Store
the 10% NaPP in refrigerator for up to 2 months.
1.3.2 10% Tween 80-1% Antifoam Y-30 solution: Pipet 0.1 mL Antifoam Y-30 Emulsion
(Sigma Cat. No. A5758 or equivalent) and 1 mL Tween 80 (Fisher Cat. No. T164 or
equivalent) into 15 mL conical tube containing 8.9 mL reagent-grade water. Vortex for
30 seconds to mix. Solution can be stored at room temperature for 1 month.
1.3.3 Elution solution (0.01% Tween® 80. 0.01% NaPP and 0.001% Antifoam Y-30): Add 0.5
mL of the 10% Tween 80-1% Antifoam Y-30 solution and 0.5 mL of 10% NaPP to 500
mL of sterile reagent-grade water. Swirl to mix. Solution can be made up to 24 hours in
advance and stored in a refrigerator. Bring to room temperature prior to use.
Note: The elution solution should be made in or transferred to a sterile 1-L heavy duty polypropylene
bottle with closed cover.
1.3.4 0.01% NaPP solution (filter wash) - 1 L: Add 1 mL of 10% NaPP solution to 999 mL of
reagent-grade water and swirl to mix. Solution can be made up to 24 hours in advance
and stored in a refrigerator. Bring to room temperature prior to use.
1.3.5 1% Bleach solution (for tubing decontamination) - 500 mL: Add 5 mL bleach to 495 mL
reagent grade or deionized water and swirl to mix. Solution can be stored at room
temperature for 1 week.
1.3.6 70% Ethanol solution (Fisher Scientific Cat. No. 04-355-56 or equivalent)
1.3.7 Sodium thiosulfate solution: Prepare 10% w/v sodium thiosulfate by adding 100 g
sodium thiosulfate (Fisher Scientific Cat. No. S446 or equivalent) to 1 L of sterile
reagent-grade water and mix well. Store at 4°C for up to 1 month.
1.3.8 Dialyzed Fetal Bovine Serum (FBS) (Fisher Scientific Cat. No. SH3007303 or
equivalent)
1.3.9 Phosphate buffered saline (PBS) (Fisher Scientific Cat. No. BP3991 or equivalent)
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Detection of Bacillus anthracis in Environmental Samples
1.4 Pre-treat the Rexeed ultrafilter with dialyzed 5% FBS in water to block non-specific protein
binding.
1.4.1 To make 150 mL of 5% FBS, add 7.5 mL of FBS to 142.5 mL of reagent-grade water.
1.4.2 Before adding the FBS to the filter, secure the ultrafilter to ring stand with a 3 prong
clamp. Ensure the bottom port is securely closed with a blood port storage screw cap.
Place the white port caps that come with the ultrafilter onto both side ports, leaving them
loosened to allow air to escape.
1.4.3 Load the ultrafilter with approximately 120 mL (no more than 150 mL) of 5% FBS by
injecting it into the top port of the ultrafilter (a 60 mL syringe with no needle works well
for this application). Attach 3" of #24 tubing to a small filter connector, secure with a #4
clamp, screw into the filter port, and insert the tip of the syringe into the #24 tubing.
Pour 60 mL of FBS solution into the syringe and use the plunger to push the solution into
the ultrafilter. Repeat for remaining volume.
1.4.4 When the ultrafilter is loaded, close the open end of the ultrafilter with a second blood
port storage screw cap and ensure side ports are closed with white port caps (they will
"click" into place).
1.4.5 Place the ultrafilter on a rocker panel at room temperature; rock for 30 minutes.
Note: Do not store the filter after pretreating, as this will encourage growth of contaminating
bacteria which may clog the filter.
1.5 Pre-treat the Water Sample
Note: Any procedure in which sample containers are opened should be performed inside a BSC.
1.5.1 If sodium thiosulfate was not added to the sample at the time of collection, add 0.5 mL/L
of a 10% w/v solution of sodium thiosulfate immediately upon receipt of the sample.
1.5.2 Pretreatthe water sample withNaPPto reach a final concentration of 0.01%. To achieve
a 0.01% concentration of NaPP, add 1 mL of 10% NaPP per 1 L of water sample.
1.6 Prepare the empty filtrate container(s) by adding a sufficient volume of bleach such that the final
concentration is at least 1% bleach (e.g., 200 mL bleach in a 20 L container).
1.7 Assembly of the Sample Tubing Set
1.7.1 Remove both ends (tip and end containing cotton material) of a 10 mL pipet by carefully
breaking off the ends while the pipet is within its plastic wrapping (Figure 1, a). Keep the
plastic sleeve to place the sample pipet in during changing of sample containers.
1.7.2 Connect the 10 mL pipet to 14" of #24 Masterflex® (MF) tubing (Figure 1, b) and secure
with a medium hose clamp (#8 plastic) (Figure 1, #1).
1.7.3 Connect the #24 tubing to one of the small 1/4" barbs on the Y connector (Figure 1, c)
and secure with a small hose clamp (#4 plastic or 7/32" to 5/8" stainless steel) (Figure 1,
#2).
1.7.4 Connect 21" of #36 tubing (Figure 1, d) to the end of the large filter connector (Figure 1,
e) and secure connection with large hose clamp (#10 plastic) (Figure 1, #3).
1.7.5 Connect the other end of the #36 tubing to the large 3/8" barb on the Y connector (Figure
1, c) and secure with a large hose clamp (#8 plastic) (Figure 1, #4).
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Detection of Bacillus anthracis in Environmental Samples
1.7.6 Connect 6" of #24 tubing (Figure 1, f) to the open small 1/4" barb on the Y connector
(Figure 1, c) and secure with a small hose clamp (#4 plastic or 7/32 to 5/8" stainless steel)
(Figure 1, #5). Connect the opposite end to the empty port on the 1 L vented cap bottle
and secure with a stainless steel clamp (vented cap bottle not shown in Figure 1, #6; see
Figure 7a, #10).
1.8
Figure 1. Sample tubing set assembly.
Assembly of the Retentate Return Tubing Set
1.8.1 Connect 15" of #24 tubing (Figure 2, a) to the small filter connector (Figure 2, b); secure
connection with a small hose clamp (#4 plastic or 7/32" to 5/8" stainless steel) (Figure 2,
c).
1.8.2 Attach a flow regulator tubing clamp (Figure 2, d) to the #24 tubing so that the wide end
is facing the 1 L vented cap bottle (Figure 2, e).
1.8.3 Connect the opposite end of the #24 tubing to the port on the 1 L vented cap bottle that is
attached to the shorter internal tubing (Figure 2, f; Figure 7a, #9); secure with a stainless
steel clamp (Figure 2, g)..
Figure 2. Retentate return tubing set assembly.
1.9 Assembly of the Filtrate Tubing Set
1.9.1 Remove both ends (tip and end containing cotton material) of a 10 mL pipet by carefully
breaking off the ends while the pipet is within its plastic wrapping (Figure 3, a).
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Detection of Bacillus anthracis in Environmental Samples
1.9.2 Connect the 10 mL pipet to 16" of #36 MF tubing and secure with a medium hose clamp
(#8 plastic) (Figure 3, b).
Figure 3. Filtrate tubing set assembly.
1.10 Connection of the Pumping Station
Note: The pumping station and ultra/liter setup may be assembled inside of a BSC or on the bench
top (bench top allows ease of assembly, but it is recommended that this protocol not be
performed on the bench). Additionally, absorbent underpads/diapers may be placed under the
UF setup and containers to capture any potential leaks or spills that may occur during sample
processing or disassembly.
1.10.1 Raise the pump to a height equal to or above the top of the reservoirs by placing the
pump on a shelf or raising it on a variable height platform such as the Jiffy-Jack®
apparatus positioner. Also, secure the filter and the 1 L vented cap bottle in a vertical
position by using adjustable metal clamps and a ring stand.
1.10.2 Connect the sample reservoir to the ultrafilter using the sample tubing set. Attach the
large filter connector on the end of the sample tubing set to the top port of the ultrafilter.
Feed the #36 tubing through the pump head, and ensure the tubing remains securely
clamped to the large filter connector.
1.10.3 Attach the small filter connector on the end of the retentate return tubing set to the bottom
port of the ultrafilter.
1.10.4 Connect the ultrafilter to the filtrate reservoir by connecting the filtrate return tubing set
to the top side port of the ultrafilter (may secure with #12 plastic clamp, but not required)
and placing the 10 mL pipet into the filtrate reservoir. Ensure the other side port is closed
with the plastic cap provided with the filter.
1.10.5 The assembled UF setup should appear as in Figures 7a and 7b.
1.10.6 Place a 1 L beaker next to the UF setup and another 1 L beaker next to the filtrate setup.
Use beakers to hold the sample and filtrate tubing pipets when changing sample and
filtrate containers to prevent potential water droplets from dripping onto the BSC.
1.10.7 Verify that the MF tubing is threaded through the pump head correctly (Figure 4).
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1.10.8 Set the pump to -50% power. If using a digital pump, the flow rate should be set to 1450
mL/min.
1.10.9 If the pump has a flow direction toggle switch, confirm the flow direction is set to the
right (Figure 4).
Figure 4. Photo of the pump head.
1.11 Washing the Ultrafilter
1.11.1 Wash the 5% FBS from the ultrafilter by placing the sample tubing end (Figure 5, #2)
into the 1 L bottle containing 0.01% NaPP filter wash prepared in Section 1.3.3 (Figure 5,
#1).
1.11.2 Detach the retentate return tubing set (Figure 5, #5) from the 1 L vented cap bottle
(Figure 5, #7) and place the end in the filtrate reservoir (Figure 5, #6) so that the retentate
return tubing set and the filtrate tubing are both in the filtrate container.
1.11.3 Apply the pinchcock to the tubing from port C (clamp the tubing from vented cap bottle
to the Y connector, getting as close to the Y connector as possible) (Figure 7a, #1).
1.11.4 Start the pump (Figure 5, #3) and flush the 0.01% NaPP filter wash through the lines and
the ultrafilter (Figure 5, #4).
Note: While flushing the NaPP filter wash, be sure to check the tubing and connections for any leaks
or drips throughout the system.
1.11.5 When the filter wash is completed, reset the tubing as shown in Figure 7a.
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Figure 5. Schematic of Filter Wash
(1) Sterile water wash, (2) Sample tubing, (3) Pump, (4) Ultrafilter,
(5) Retentate tubing set, (6) Filtrate reservoir, (7) 1 L vented cap bottle
2.0 Primary Water Sample Concentration
2.1 With the sample container in place and the tubing set per Figure 7a, check to make sure the
pinchcock is applied to the tubing from port C (Figures 7a and 7c, #1), the vented cap is securely
tightened to the bottle, and the rubber cap is removed from the vented cap.
Note: When applying the pinchcock clamp to the tubing, make sure it is clamped as close to the Y
connector as possible to completely block and/or stop the flow of water through tubing (Figure
7c, #1).
2.2 Start the pump with the flow switch turned to the right and the pump speed set to the maximum
(~ 2900 mL/min flow rate).
2.3 Once the 1 L retentate bottle is -2/3 of the way full, quickly close the open port of the vented cap
with the rubber cap and remove the pinchcock from the tubing (Figures 7a and 7c, #2). The
pump will now be drawing water from both the sample container and the 1 L vented cap
(retentate) bottle. Make sure the water level in the 1 L retentate bottle does not continue to rise.
If the water level in the 1 L bottle does rise, remove the rubber cap and apply pinchcock to the
tubing from port A (Figures 7a and 7c, #3). Once the water level in the 1 L bottle is 2/3 of the
way full, close port with rubber cap and remove the pinchcock (Figures 7a and 7c, #2).
2.4 Tighten the flow regulator by rolling the knob to the right until the "K" in the "KT" lettering on
the front face of the flow regulator is directly in the middle of the adjustment knob (Figure 6).
The back pressure provided by the flow regulator should produce a filtrate rate between 1000 -
1400 mL/min.
Note: The flow rate does not need to be measured.
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Detection of Bacillus anthracis in Environmental Samples
Figure 6. Position flow regulator rolling clamp over "K" in "KT".
Y Connector
Y Connector and pinchcock:
1. Clamp tubing from port C at
beginning of filtration. Water
flows from sample container
through ultrafilter to fill 1L
bottle.
2. Remove pinchcock when the
volume in the 1L bottle is 2/3
full. The system then draws
from both 1L bottle and
sample container.
3. Clamp tubing from port A
once the entire sample is
drawn from the sample
container. Sample is now
being reduced in the 1L bottle
only.
Peristaltic Pump
Flow
Hollow Fiber
Ultrafilter
5. Filtrate
tubing
Sample
container
L/S 24 tubing
(AandC
ports)
L/S 36 tubing
(B port)
6. Empty container
(filtrate)
Figure 7a. Recirculating ultrafiltration assembly.
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Detection of Bacillus anthracis in Environmental Samples
Figure 7b. Photograph of the ultrafiltration system set up inside a BSC.
Figure 7c. Pinchcock positions.
2.5 When the sample container is empty, apply the pinchcock to clamp the tubing from port A
(Figures 7a and 7c, #3), loosen the flow regulator and turn off the pump.
Note: Whenever the pump needs to be stopped, apply thepinchcock to clamp the tubing from port A
so that the water containing microbes cannot flow back into the sample tank and then quickly
press the stop button.
2.6 If this is the only sample container, skip to step 2.13.
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2.7 Remove the sample tubing set from the empty sample container and carefully place it in a sterile
1 L beaker. Remove the filtrate pipet in the same manner and place in a second sterile 1 L
beaker.
Note: To prevent drips, ensure the pipet is free of any remaining sample while still inside the sample
container. Labs may consider placing the pipet back into the plastic sleeve prior to placing it
into the 1L beaker. Alternatively, if sample container is disposable, the tubing may be cut and
the pipet can be disposed of inside the sample container.
2.8 Remove the empty sample container and replace with the next sample container to be filtered.
Also replace the full filtrate container with an empty filtrate container [containing 1% bleach as
directed in Section 1.3.4].
Note: Follow Biosafety in Microbiological andBiomedical Laboratories (BMBL) and lab-specific
safety practices for BSL-3 working conditions while slowly moving containers into and out of
the BSC. Let airflow re-establish for a minimum of 15 minutes each time the sash is lifted.
2.9 Place the sample tubing set into the new sample container and the filtrate tubing set into the new,
empty filtrate container.
2.10 Turn the pump back on and remove the pinchcock from the tubing from port A (Figures 7a and
7c, #2) so that the water is once again being drawn from both the container and the 1 L bottle.
2.11 Tighten the flow regulator to the same position described in Section 2.4 and continue filtration.
2.12 Repeat steps 2.7-2.11 for the rest of the containers.
2.13 When the last container has been emptied, apply the pinchcock to clamp the tubing from port A
(Figures 7a and 7c, #3) so that the sample is only being re-circulated in the 1 L bottle, loosen the
flow regulator, and remove the rubber cap from the 1 L bottle.
2.14 When the sample in the 1 L bottle draws down to about 1.5" from the bottom, move the
pinchcock to clamp the tubing from port C (Figures 7a and 7c, #1), so that only air is being drawn
into the filtration system by the pump.
Note: Continue flushing until all the retentate is out of the tubing and the filter. The retentate tubing
may be lifted 2-3 times to help flush the water that has settled in the retentate tubing into the 1
L bottle.
2.15 Turn off the pump when all of the retentate has been flushed from the tubing and the filter. The
final volume should be approximately 200 mL - 250 mL.
2.16 Carefully unscrew the steel clamps from the ports on the vented cap bottle and remove the tubing
connections from the top ports (containing the concentrated sample). Place them onto the ports of
the second vented cap bottle containing the elution solution and secure the clamps (remove the
closed cap from the elution solution bottle first).
2.17 Unscrew the vented cap from the first bottle containing the sample. Lift and securely hold the
cap with one hand (tubing remains inside the bottle) while using a 25 mL or 50 mL pipet in the
other hand to measure and transfer the sample retentate into a sterile, 1 L plastic bottle. Record
the retentate volume.
2.18 Secure the second vented cap bottle containing the elution solution with the 3-pronged clamp
from the first vented cap bottle. Check that the flow regulator is fully opened, the pinchcock is
clamped to the tubing from port A (Figures 7a and 7c, #3) and the rubber cap is removed from the
1 L vented cap bottle. The assembly should now be ready for elution of the ultrafilter.
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2.19 Turn on the pump, allowing the eluent volume to gradually reduce until the level draws down to
1.5" from the bottom of the bottle. Move the pinchcock to clamp the tubing from port C (Figure
7a and 7c, #1) to flush the rest of the eluent from the tubing and filter. Turn off the pump.
2.20 Unscrew the vented cap assembly from the second bottle containing the concentrated eluent. Lift
and securely hold the cap with one hand (tubing remains inside the bottle) while using a 25 mL or
50 mL pipet in the other hand to measure and transfer the eluent to the 1 L plastic sample bottle
containing the retentate. The total volume of the final UF concentrate should be 400 mL - 500
mL.
3.0 Secondary Water Concentration
3.1 Inside of a BSC, assemble the membrane filtration setup shown in Figure 9, ensuring the HEPA
filter (Vacushield) is attached with #24 tubing (or alternative vacuum tubing) to the house
vacuum and the side arm of the back-up flask. Connect the side arm of the main flask to the
stopper of the back-up flask with vacuum tubing. This tubing length should be long enough such
that the tubing rests on the surface of the BSC to help stabilize the flasks. Attach an additional
piece of vacuum tubing to the side arm of the main flask for connection to the disposable filter
units.
3.1.1 Use the piece of #24 tubing from the side arm of the main filter flask to attach the quick
disconnect side arm on the filter unit (Figure 9, #5) and use sterile forceps to place a new filters
onto the base of each filter unit (Figure 9, #3).
Note: Disposable filter units (Section 1.1.8) come with cellulose nitrate membrane filters, which must
be replaced with the mixed ester cellulose filters. DO NOT remove the cellulose support pad on
the base of the unit when replacing membrane filters. It is recommended to keep a small
autoclave bag inside the BSC during processing for safe disposal of filter funnels.
Figure 9. Membrane filtration setup.
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3.2 Run a negative control before filtering any sample concentrate. Add 20 mL PBS to the filter cup
(Figure 9, #2) and turn on the vacuum. Once the PBS has finished filtering, turn off the vacuum
and remove the cup from the base of the filter unit (Figure 9, #3). Retrieve the membrane filter
with sterile forceps and place onto a SBA plate. Incubate at 37°C ± 1°C for a maximum of 3
days.
3.3 Use sterile forceps to place a new 0.45 (im filter onto the support pad on the base of the filter unit.
Reattach the filter cup to the base.
3.4 Add the retentate slowly to the filter unit (Figure 9, #2) and turn on the vacuum (not all the
retentate will fit at once). Continue to add retentate to the filter unit taking care to avoid clogging
the filter. Once the sample has finished filtering, rinse the filter cup 3 times with PBS in a squirt
bottle. Turn off the vacuum; remove the filter cup from the bottom portion (Figure 9, #3) of the
filter unit and set it on a sterile surface.
Note: If the final retentate is particularly cloudy or has noticeable sediment, it might be necessary to
split the retentate volume between two or more filter units.
3.5 Using sterile disposable forceps, grab the edge of the membrane at the filter unit base and fold it
toward the other end. While holding the 2 edges together, take the forceps and place folded
membrane into the bottom half of a 50 mL conical tube, avoiding the conical portion. Close tube.
3.6 Repeat steps 3.1 - 3.4 for the remaining samples.
Note: If multiple filtrations were run due to excess sediment, process all of the membrane-filters.
3.7 For polymerase chain reaction (PCR) analysis, proceed to Section 9.1.5 of the protocol.
3.8 For Rapid Viability-PCR (RV-PCR) analysis, proceed to Section 10.2.6 of the protocol.
3.9 For culture analysis, proceed to Section 11.5 of the protocol.
4.0 Limitations
4.1 If the procedure is not performed correctly, it may result in false negative results.
4.2 Water from certain sources may contain higher levels of minerals, organic compounds or other
substances which may affect the water concentration procedure and subsequent testing
procedures for the detection of potential BT agents.
4.3 The presence of chlorine-based disinfectants in the water supply will inhibit or prevent the growth
of most microorganisms. Sodium thiosulfate should be added as soon as possible to inactivate
chlorine in the water. Addition of sodium thiosulfate at the time of collection of the water sample
is recommended.
4.4 Even with the addition of sodium thiosulfate, some organisms may not survive the filtration
process and may only be detected by real-time PCR.
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Detection of Bacillus anthracis in Environmental Samples
5.0 Acronyms
BMBL Biosafety in Microbiological and Biomedical Laboratories
BSC Biological safety cabinet
BSL Biological safety level
BT Bioterrorism threat
FBS Fetal bovine serum
MF Masterflex®
NaPP Sodium poly-phosphate
PBS Phosphate buffered saline
PCR Polymerase chain reaction
RV-PCR Rapid viability-polymerase chain reaction
SOP Standard operating procedure
UF Ultrafiltration
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&EPA
United States
Environmental Protection
Agency
PRESORTED STANDARD
POSTAGE & FEES PAID
EPA
PERMIT NO. G-35
ice of Research and Development
•—-' "----^---'^-Tjrity Research Center
Mational Homeland Security
Cincinnati, OH 45268
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