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FAQ -
Mycobacterium abscessus
The following text was prepared by the
Toronto Public Health Department and given to Health Care
Providers following the outbreak
What is Mycobacterium abscessus?
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Mycobacterium abscessus (M. abscessus), also known as
Mycobacterium chelonae subspecies abscessus in the past, is
a rapidly growing atypical non-tuberculous mycobacteria. It
is ubiquitous in the environment and can be found in water,
soil, and dust, as well as in animals. It is resistant to
chlorine so can be found in municipal or well water treated
with chlorine. It can also grow in other chemical
disinfectants such as gluteraldehdye. |
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What illnesses can M. abscessus cause?
M. abscessus rarely causes illness in humans. It has
occasionally been associated with a variety of illnesses and
clinical syndromes including skin and soft-tissue infections
(following puncture wounds or inoculations with contaminated
medication), pulmonary infection, infections related to
foreign material (e.g., porcine and prosthetic cardiac
grafts, prosthetic joints, intravenous and dialysis
catheters, tympanoplasty tubes, and augmentation mammoplasty),
and post-surgical infections. Rare disseminated disease,
usually with disseminated skin and soft tissue lesions,
occurs almost exclusively in the setting of
immunosuppression (e.g. AIDS).
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What is the incubation period for M. abscessus?
Although most people will have symptoms of illness within
one month of exposure to M. abscessus, incubation periods of
up to 1 year have been documented.
Who is at risk of developing infection with M. abscessus?
People of all ages are at risk if exposed. Although healthy
people occasionally develop infections with this bacteria,
the disease may be more severe in immunocompromised
patients.
How is M. abscessus spread?
M. abscessus is not spread directly from person to person.
It causes illness most frequently when it enters wounds
(traumatic or surgical) or contaminates injectable
medication or medical devices that are placed under the
skin. Clusters of cases of M. abscessus infection have
mostly been associated with non-sterile water, contaminated
surgical instruments and injectable medication, especially
injectable medication dispensed in multi-dose vials.
Outbreaks have been linked to multi-dose vials of lidocaine
and adrenal extract.
What symptoms are caused by M. abscessus?
The type of illness will depend on the infection site.
Individuals with abscesses due to M abscessus will initially
experience painless nodules that become erythematous,
swollen and painful. Ulcerative lesions may develop that may
drain small amounts of purulent discharge. In some cases
fever and chills may also occur.
How can I diagnose M. abscessus?
Diagnosis of M. abscessus infection relies on culture and
identification of the organism. Although swab culture of
visible skin lesions and aspirates of fluid collection can
all be sent for atypical mycobacteria culture the preferred
test is culture of a skin biopsy. The Central Public Health
Laboratory (CPHL) can perform these tests. Rapidly growing
mycobacteria such as M. abscessus can be cultured in 5 to 8
days on specific culture media but further testing is
required to rule out diphtheroids which resemble M.
abscessus. Species identification and susceptibility testing
can also be conducted at the CPHL.
How is this infection treated?
A combination of surgical drainage and antibiotic therapy
may be necessary to ensure cure of infections with M.
abscessus. Many isolates of M abscessus are susceptible to
clarithromycin, amikacin, imipenem, and cefoxitan but
variations in resistance patterns make it imperative to
determine the drug susceptibilities of each clinical
isolate. Monotherapy may be considered for localized skin
infections where the risk of selection for resistance
appears to be lower. Combination chemotherapy with at least
two antimicrobial agents to which the isolate is susceptible
is advised for disseminated disease because monotherapy has
been shown to contribute to the development of resistance.
Localized disease typically responds to 6 months of
monotherapy with clarithromycin in immunocompetent hosts.
Disseminated infections can require greater than 6 months of
antibiotic therapy. |
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Last modified
17/02/04
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© 2001-2004 Paul Harte Professional Corporation. All rights reserved.
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