Test Method for the Continuous Reduction of Bacterial Contamination
on Copper Alloy Surfaces
Test Organisms: Staphylococcus aureus (ATCC 6538)
Enterobacter aerogenes (ATCC 13048)
Pseudomonas aeruginosa (ATCC 15442)
Methicillin Resistant Staphylococcus aureus MRSA (ATCC 33592)
Escherichia coli O157:H7 (ATCC 35150)
Sanitizer efficacy testing must be conducted against Staphylococcus aureus
(ATCC 6538) and Enterobacter aerogenes (ATCC 13048), before additional
organisms or claims (residual self-sanitizing activity and continuous reduction)
are considered. Acceptable efficacy testing is required against Staphylococcus
aureus (ATCC 6538) and Enterobacter aerogenes (ATCC 13048) as a non-food
contact sanitizer before additional microorganisms or claims can be granted. For
claims of Continuous Reduction and/or Residual Self-Sanitizing Activity, initial
efficacy testing against Staphylococcus aureus and Enterobacter aerogenes is
required before additional microorganisms are granted.
Test System
Carrier Surfaces and Preparation: Cut copper alloy into individual 1" x 1" square
carriers. Stainless steel carriers (1" x 1") must be incorporated into the test system.
Copper alloy surfaces will be utilized as the test carriers and stainless steel squares as
control carriers for this assay. Clean carriers with alcohol, rinse with deionized water,
and allow to air dry. Sterilize carriers prior to use in test. After sterilization, place each
carrier into a plastic Petri dish matted with two pieces of filter paper using sterile forceps.
Test five (5) test carriers per material per organism per time point.
Preparation of Test Organisms
Staphylococcus aureus, Pseudomonas aeruginosa, Methicillin Resistant Staphylococcus
aureus: From stock cultures, inoculate tubes of the appropriate broth with organism, and
incubate for 24±2 hours at 35-37°C. Using a 4-mm inside diameter disposable sterile
plastic transfer loop, transfer at least three consecutive daily cultures in appropriate
broth prior to use as inoculum. Transfer two (2) loopfuls of culture into 10 ml broth
medium. Transfers more than 15 days away from stock culture should not be used for
the inocula for this test. On the day of use, aspirate pellicle from the Pseudomonas
aeruginosa culture.
Enterobacter aerogenes: From stock cultures, inoculate tubes of Tryptic Soy broth
(TSB) and incubate for 24±2 hours of 25-30°C. Using a 4-mm inside diameter
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disposable sterile plastic transfer loop, perform at least three consecutive daily transfers
of cultures in Tryptic Soy Broth prior to use as inoculum. Transfer two (2) loopfuls of
culture into 10 ml broth medium. Transfers more than 15 days away from stock culture
should not used for the inocula for this test. Use the 24-54 hour cultures for the inocula
in this test.
For each test organism, thoroughly mix the culture on a "vortex" mixer and allow to
settle. Aspirate the upper two thirds of this suspension and use as the inoculum for
testing. Add an organic soil load containing Triton X-100 (to aid in spreading the
inoculum) to the test culture.
Addition of Organic Soil Load: Add 0.25 ml aliquot of serum + 0.05 ml Triton X-100 to
4.70 ml bacteria suspension to yield a 5% fetal bovine serum and 0.01% Triton X-100.
Antimicrobial Susceptibility Testing (if applicable): Antimicrobial susceptibility
testing is required when utilizing a resistant organism. Before testing, verify the
antimicrobial resistance pattern of Methicillin Resistant Staphylococcus aureus (MRSA).
Subculture the organism onto a Tryptic Soy agar (TSA) plates (or 5% sheep blood agar
plates (BAP)), and incubate for approximately 24 hours at 35-37°C. Following
incubation, make a suspension of the test organism equal to 0.5 McFarland Standard in
0.85% sterile saline. Streak the suspension onto Mueller Hinton agar. Place an oxacillin
disc in the center of the inoculated Mueller Hinton plate. Invert and incubate for > 24
hours at 35-37°C. Following incubation, measure the zone of inhibition using a
calibrated caliper. Concurrently run Staphylococcus aureus (ATCC 25923), a control
organism, with the test organism to confirm the validity of the assay. The interpretation
of the zone of inhibition is based on established National Committee for Clinical
Laboratory Standards (NCCLS) performance standards.
Inoculation of Carriers: Use five (5) sets of five test carriers and five sets of three
control carriers in this study. Inoculate all carrier sets at time zero. Inoculate each
sterile test carrier at staggered intervals with 5 ul of culture using a calibrated pipette.
Spread the inoculum on the surface of the carriers. Dry the carriers at ambient
conditions for the duration of the exposure. The exposure period begins with the initial
inoculation of the carrier.
Re-inoculate carrier sets not removed for quantitative recovery as follows at 3, 6, 9, 12,
15, 18, and 21 hours (as described above).
Neutralization and Subculture: Remove sets of test and control carriers for
quantitative recovery at 2, 6, 12, 18 and 24 hours. These carriers were inoculated 1, 2,
4, 6 and 8 times, respectively. At each recovery time, transfer the carriers into individual
containers with 20 ml of the Letheen broth (or appropriate neutralizer). Sonicate each
neutralizer container for five minutes to suspend any survivors from the carriers, and
rotate to mix. Within one hour after sonicating the carriers, prepare serial dilutions (10"1 -
10"4) of the neutralized solution from each of the containers and plate in duplicate for
survivors using standard spread plate technique and TSA plates (5% sheep blood agar
plates).
Incubation and Observation: Incubate the plates at 35-37°C for 48±4 hours (Incubate
E. aerogenes plates at 25-30°C for 48±4 hours) prior to observation for number of
colonies. Visually enumerate the plates. Stain and/or biochemically assay to confirm or
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deny the presence of the test organism. If possible, use subcultures containing 30-300
colonies for calculations.
Study Controls
Purity Controls: Perform a "streak plate for isolation" on each organism culture and
following incubation examine in order to confirm the presence of a pure culture. The
acceptance criterion for this study control is a pure culture demonstrating colony
morphology typical of the test organism.
Organic Soil Sterility Control: Culture, incubate, and visually examine the serum used
for soil load. The acceptance criterion for this study control is lack of growth.
Carrier Sterility Control: Add a representative uninoculated test and control carrier to
the neutralizing subculture medium. Incubate and examine for growth the subculture
medium containing each carrier. The acceptance criterion for this study control is lack of
growth.
Neutralizing Subculture Medium Sterility Control: Incubate and visually examine a
representative sample of uninoculated neutralizing subculture medium. The acceptance
criterion for this study control is lack of growth.
Viability Control: Add a representative inoculated control carrier to the subculture
medium. Incubate and visually examine the subculture medium containing the carrier for
growth. The acceptance criterion for this study control is growth.
Neutralization Confirmation Control: Perform the neutralization confirmation control
to demonstrate the neutralizer's ability to inactivate the test carrier. The neutralization of
the test carriers is confirmed by using sterile test carriers and neutralizing as in the test
procedure. A 1.0ml aliquot of a diluted suspension of the test organism yielding <100
CFU/ml of neutralizing subculture medium is transferred to the jar and mixed. A 1.0 ml
aliquot of this mixed solution is plated in duplicate. A numbers control is performed
utilizing sterile stainless steel control carriers. The resulting plates are incubated as in
the test and enumerated. The acceptance criterion for this study is growth within 1 Iog10
of the numbers control.
Inoculum Count: Serial dilutions of the cultures used as the inocula are prepared and
plated. TSA plates (or 5% sheep blood agar plates) are used for all organisms.
Incubate the resulting plates for 48±4 hours at 35-37°C, and then count the colonies to
determine the number of organisms per milliliter of inoculum present at the start of the
test.
Carrier Quantitation Control: Use three (3) inoculated stainless steel control carriers
to determine the number of test organisms per carrier at each quantitative recovery time
point. Transfer the control carriers to neutralizing subculture media and sonicate as in
the test. Prepare ten-fold serial dilutions of the neutralizing subculture medium and plate
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1.0 ml of the appropriate dilutions in duplicate to yield countable numbers. Incubate and
enumerate the plates as in the test. The acceptance criterion for this study control is a
minimum geometric mean of 2.0 x 104 CPU/carrier.
Study Acceptance Criteria
Test Substance Performance Criteria
To support a claim for continuously reducing bacteria on a copper alloy surface, a
minimum of a 90% reduction in numbers of the test organism(s) on the test surface
compared to the number of test organism(s) on the control surface must be achieved at
all recovery times over the 24 hour inoculation and exposure period.
Control Acceptance Criteria
The study controls must perform according to the criteria detailed in the study controls
description section.
Data Analysis
Calculations
Number of Organisms Surviving per Carrier
CFU/carrier= (average number colonies/plate @. dilution) X (dilution factor) x (volume neutralized solution)
(volume plated)
The carrier population was calculated and reported using data from the most appropriate dilution(s).
Geometric Mean Number of Organisms Surviving on Control Carrier
Geometric Mean= Antilog of Log-ir^ + LoginX2 + Log^nX^
3
Where X equals CPU/control carrier
Geometric Mean of Number of Organisms Surviving on Test Carrier
Geometric Mean= Antilog of Log^nY^ + Log^nY^+ Log^Y^ + Log^Yj + LogWYg
5
Where Y equals CPU/test carrier
Percent Reduction
% reduction = [(a-b) / a] x 100
Where:
a= geometric mean of the number of organisms surviving on the inoculated control
carriers
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b= geometric mean of the number of organisms surviving on the test carriers.
Recovery Log10 Difference = (Log10 Numbers Control) - (Log10 Test Results)
Used to calculate the neutralization confirmation control
Statistical Methods
Geometric Mean and Percent Reduction. Three digits were used when reporting Log, Average
Log, Geometric Mean, and Percent Reduction values.
Label Claims Supported By the Protocol.
1. This surface continuously reduces bacterial* contamination.
2. This surface provides continuous/ongoing/persistent antimicrobial action even
with repeated exposures.
3. This surface continuously kills over 90% of bacteria* after repeated exposures
during a day.
4. This surface prevents the buildup of disease-causing bacteria*.
5. This surface delivers continuous, long-lasting antibacterial* activity.
* Includes list of tested organisms.
Claims are limited to indoor, hard, non-porous surfaces where cleaning practices are consistent
Required Label Language
The use of a Copper Alloy surface is a supplement to and not a substitute for standard
infection control practices; user must continue to follow all current infection control
practices, including those practices related to cleaning and disinfection of environmental
surfaces. The Copper Alloy surface material has been shown to reduce microbial
contamination, but does not necessarily prevent cross contamination.
Proper Care and Use of Antimicrobial Copper Alloys: The use of Antimicrobials Copper
Alloys does not replace standard infection control procedures and good hygienic
practices. Antimicrobial Copper Alloys surfaces must be cleaned and sanitized
according to standard practice. Heath care facilities must maintain the product in
accordance with infection control guidelines; users must continue to follow all current
infection control practices, including those practices related to disinfection of
environmental surfaces.
Cleaning Directions: Routine cleaning to remove dirt and filth is necessary for good
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sanitization and to assure the effective antibacterial performance of the Antimicrobial
Copper Alloy surface. Cleaning agents typically used for traditional touching surfaces
are permissible; the appropriate cleaning agent depends on the type of soiling and the
measure of sanitization required.
This product must not be waxed, painted, lacquered, varnished, or otherwise coated.
The following are a listing of Conditions of Registration for Antimicrobial Copper
Alloy registrations and associated labeling issues:
Condition 1
The registrant will prepare and implement an Antimicrobial Copper Alloy Stewardship
plant to support the responsible use of antimicrobial copper products. The Plan will be
submitted for EPA review and approval within two months after the registration date. If
EPA determines at any time after 18 months following registration that the Plan is not
being adequately or timely implemented or that implementation of the Plan is not
effectively ensuring the proper sale, distribution, or use of antimicrobial copper alloy
products, the registration may be automatically canceled by the Agency by order with
opportunity for a hearing but only after notification to the Registrant and an opportunity to
meet with the Director of the Office of Pesticide Programs.
The Plan will include, at a minimum, the following elements:
(a) Outreach to the infection control community, including,
(i) A goal of educating and reinforcing, for infection control professional and
other product users, the proper use of Antimicrobial Copper Alloys.
(ii) Written (including electronic) communications directed to associations of
infection control professionals, including at least the APIC, ASHES, and
any other relevant organizations identified by CDA or EPA, and State
Departments of Health.
(iii) Outreach communications will be sent within six months after the date of
registration and within one year after the date of registration, and then
annually thereafter on the anniversary of the date of registration unless
more frequent outreach is deemed necessary.
(iv) The content of the outreach communications will include statements
explaining the registered claims and applications of Antimicrobial Copper
Alloys, as well as their proper use. The communications also will inform
the recipients about (1) the Antimicrobial Copper Alloy Working Group,
and invite participation; (2) other sources of information on Antimicrobial
Copper Alloys, including the Stewardship Website. Additional content of
outreach efforts will be developed as part of the Working Group activities.
(b) Development of Website
(i) The website will serve as a resource for conveying accurate information
to the public about the efficacy and proper use of Antimicrobial Copper
Alloys.
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(ii) The website will include information on proper labeling and claims
(including advertising); supporting science; applications; maintenance;
and federal and state regulations and statutory requirements.
(iii) A question and answer of Frequently Asked Questions (FAQs) section
will be incorporated to address common issues or questions raised with
regard to Antimicrobial Copper Alloys.
(iv) The website also serves as a forum to correct any false or misleading
third party statements or publications, including scientific papers,
concerning antimicrobial Copper Alloys. Any such false or misleading
third party statements of publications will be corrected promptly after the
registrant becomes aware of such and the responsive website update will
be incorporated promptly thereafter. The registrant will inform EPA within
30 calendar days following its receipt of any such false or misleading third
party statements or publications and at the same time provide the Agency
with a copy of such statement or publication along with a hard copy of the
Website entry correcting such statement or publication.
(v) The registrant will arrange for and establish links between the website
and the websites of appropriate infection control organization, including
but not limited to APIC and ASHES.
(c) Establishment/Participation in Antimicrobial Copper Alloy Working Group
(i) Invited participants will include alloy manufacturers, component makers,
and representatives from the infection control community, including
appropriate trade associations (e.g. APIC and ASHES) and State
Departments of Health.
(ii) The Working Group will meet at least twice a year, either in person or by
live video conferencing or teleconference.
(iii) The Working Group will serve as a forum to expand educational efforts,
develop outreach communications, and address any questions or
concerns from the public and infection control community.
(iv) The registrant will provide the Agency with minutes of any such meetings
within 60 days of the end of any such meeting.
Condition 2
For at least the first 24 months after registration or until the Agency terminates this
conditions, whichever is later, the registrant will submit to EPA sample advertising
materials. Advertising materials will be representative of advertisements intended for
use in the marketplace.
Point of Contact: Tajah Blackburn, Ph.D., (703)-308-0372
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