United States
Environmental Protection
Agency
Office of Science and Technology
Office Of Water
Washington DC, 20460
EPA-822-F-02-002
March 2002
&EPA
MYCOBACTERIA: DRINKING WATER FACT SHEET
GENERAL INFORMATION
• Mycobacteria belong to the
• • Order Actinomycetales,
•• Family Mycobacteriaceae, and
•• Genus Mycobacterium.
• There are approximately 90 recognized
species of Mycobacteria, over 20 of
which are known to cause disease in
humans.
• Non-tuberculosis mycobacteria (NTM)
have been identified in numerous
environmental sources, including water.
• There has been recent interest in the
NTM species, due to their ability to
cause disease in humans and animals
after environmental exposures.
Characteristics and Classification:
• Mycobacteria are rod-shaped bacteria
which require oxygen for growth. Each
species has an acid-fast staining
property during some stage of its
growth cycle.
• Mycobacterium have been referred to
as the 'ducks of the microbial world'
due to their thick, waxy, outer coating
which enables them to thrive in aquatic
environments.
• The various species of Mycobacteria
are classified based on their growth
rates in culture into the following three
categories: slow growers, rapid growers
and those not yet cultivated.
ENVIRONMENTAL OCCURRENCE
• NTM have been found to be ubiquitous
in the environment.
• NTM species have been isolated from
numerous water sources, including
waste water, surface water,
recreational water, ground water and
tap water.
• Piped water supplies are readily
colonized by mycobacteria. Biofilms
may serve as a reservoir for these
opportunistic pathogens.
• Few studies are available which
quantify the concentrations of NTM in
water. Some reports indicate that NTM
have been recovered in 11 % to 38% of
raw water samples at concentrations of
<0.1 to 48 organisms per milliliter of
water.
HEALTH EFFECTS IN HUMANS
Transmission to Humans:
• NTM are not thought to be transmitted
by the human to human route, but are
instead thought to be transmitted from
environmental sources.
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• Exposure pathways of potential
concern include ingestion, inhalation
and entry of organisms through
abraded skin.
Symptoms:
• The clinical symptoms seen following
infection with NTM depend greatly on
the mycobacterial species.
• Common clinical syndromes include:
•• Pulmonary infection
• • Infection of the lymph nodes
• • Ear infection
• • Skin & soft tissue infection
• • Catheter-associated infection
•• Whole Body (e.g., blood) ifection
• In general, symptoms seen in children
are similar to those reported in adults.
Pulmonary disease is relatively rare in
children. The most common form of
clinically significant NTM infection in
children is infection of the lymph nodes
in the neck.
Treatment:
• Treatment of NTM infection depends on
the location and extent of disease
involvement, status of the host's
immune system, and the mycobacterial
species.
• • Treatment of pulmonary and whole
body infections most often requires
a multidrug regimen.
• • Treatment for cutaneous lesions
may include surgical removal or
drug therapy. Often, cutaneous
lesions will disappear without
requiring treatment.
Disease Occurrence and Outbreaks:
• NTM diseases are not reportable,
therefore, information regarding the
occurrence of disease outbreaks is
likely to be underestimated. However,
human infections due to NTM appear to
be increasing at a significant rate
across the United States.
CDC estimates that NTM diseases
(non-AIDS related) occur in 1.8 out of
100,000 individuals per year in the
U.S., of which approximately 72% are
attributable to M. avium complex
(MAC).
It has been estimated that in the U.S.,
25% to 50% of individuals with AIDS
will develop NTM diseases, primarily
attributable to MAC. The recent use of
highly active anti-retro viral therapy
(HAART) in AIDS patients suggests a
decrease in the risk and rate of NTM
infections in these individuals.
Waterborne NTM have been
associated with hospital (nosocomial)
outbreaks worldwide. These disease
outbreaks usually involve sternal
wound infections, plastic surgery
wound infections or postinjection
abscesses. Mycobacterial infections in
patients undergoing dialysis treatment
have also been reported.
Although not reported frequently, some
outbreaks of mycobacterial infection
have been reported after exposures in
public swimming areas.
Some false outbreaks have been
reported as a result of contaminated
sampling equipment or water supplies
used for diagnostic procedures.
Therefore, it is important that
precautions be taken when performing
diagnostic tests in order to lessen the
chance of false-positive test results.
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HEALTH EFFECTS IN ANIMALS
• Several of the NTM species are known
to cause disease in animals. These
include MAC, M. marinum, M. ulcerans,
M. paratuberculosis, M. simiae, M.
fortuitum and M. smegmatis.
• Symptoms seen following infection
depend on the host organism and the
species of NTM.
• M. paratuberculosis is the causative
agent of Johne's disease; a slow,
progressive infection of the intestine
which occur mainly in cattle, sheep and
goats.
• M. marinum is an important cause of
death and economic loss in fish
populations.
• M. fortuitum and M. smegmatis are
known to produce mastitis in sheep and
cattle and skin and soft tissue disease
in domestic house cats.
• Destruction or isolation of infected
animals is the most common form of
treatment, however, drug therapy has
been successful in some cases.
RISK FACTORS
• The general population (healthy
individuals) is fairly resistant to
infection.
• Certain individuals are at increased risk
for developing NTM associated
diseases due to the presence of
predisposing factors, including:
• • traumatic breaches of the skin
• • pre-existing pulmonary disease or
damage
•• lung architectural defects
•• bronchiectasis
• • generalized congenital and acquired
immunosuppressive disorders (e.g.,
HIV)
ANALYTICAL METHODS
• The most common method for the
identification of mycobacterial species
in water samples is through culture
isolation. The bacterial culture is
evaluated for morphology, growth rates
and other biochemical parameters in
order to determine the species.
• Several other methods have been
developed for the detection of
mycobacteria in samples, including:
• • Polymerase chain reaction (PCR)
• • Radiometric methods (BACTEC)
•• GC/MS
• • Nucleic acid probes
• Although promising, these methods
only provide qualitative information
regarding the presence of mycobacteria
in water and do not provide a measure
of concentration.
• When collecting samples for use in
culture isolation, a decontamination
step is necessary to kill the other
bacteria and fungi present in the water.
This is because there is a large
problem of contamination of samples
due to the presence of non-
mycobacterial bacteria which are
capable of growing at faster rates than
the species of interest. Acids, alkalis
and detergents are often used during
the decontamination process since
mycobacteria are generally more
resistant to these chemicals than are
other bacteria.
WATER TREATMENT
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In general, two mechanisms can be
used to eliminate microbes from
drinking water: removal or disinfection.
Removal treatments such as filtration,
sedimentation, coagulation, flocculation
and adsorption are primarily physical
operations that remove bacteria from
the water.
Disinfection treatment technologies
may kill bacteria using chemicals such
as chlorine, ozone, bromine, iodine or
hydrogen peroxide which are added to
the water, or may inactivate microbes
via UV radiation.
NTM are relatively resistant to standard
water disinfection procedures and,
therefore, can occur in potable water.
Overall, there is little information
available regarding the effectiveness of
various disinfection treatments on
mycobacterial species in water.
However, EPA is actively studying
methods to reduce the occurrence of
Mycobacteria in drinking water and will
update this fact sheet when better
information becomes available.
zero organisms (bacteria and viruses),
including mycobacteria, for drinking
water. An MCLG is a non-enforceable
guideline based solely on an evaluation
of possible health risks, taking into
consideration a margin for public
safety.
ADDITIONAL INFORMATION
• EPA has established the Safe Drinking
Water Hotline, a toll-free number for
further information on drinking water
quality, treatment technologies, and for
obtaining Health Advisories or other
regulatory information.
• Safe Drinking Water Hotline:
800-426-4791
9:00 a.m. - 5:30 p.m. (Eastern Time)
Monday-Friday (excluding
holidays).Your state or county health
officials or experts in your state's
Department of Environmental
Protection or Natural Resources may
also be of assistance.
REGULATORY INFORMATION
• EPA has established a Maximum
Contaminant Level Goal (MCLG) of
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