|
wildlife and zoo assay data sheet
PCR panel
for
mycobacteriosis in amphibians
Test
code: P0030 -
Ultrasensitive detection of five
Mycobacterium species affecting amphibians by real time PCR.
Panel detects:
Panel does
not detect or cross-react with other mycobacteria.
P0030 is
included in P0031 -
amphibian screening panel
The
genus Mycobacterium contains more than 70 species, which
can be divided into two groups based upon their growth rate in
culture. Slow-growing species require more than 7 days to be
visible on culture, whereas the rapid-growing species require
less than 7 days. In general, many slow-growing species are
pathogenic in humans, whereas rapid-growing species are usually
considered nonpathogenic.
Mycobacteriosis
in amphibians, especially frogs, is caused by acid-fast bacilli
of the genus Mycobacterium.
Many mycobacterial species found in the environment can cause
infection in amphibians, including
M. marinum,
M. chelonae, M. ulcerans,
M. liflandii and
M. xenopi (Mve-Obiang et al., 2005, Trott et al., 2004). All these
mycobacerial species are ubiquitous in nature and can be found
in water. They are resistant to normal water treatment.
Mycobacteriosis
is a serious threat to the health of a frog colony, although
tuberculosis usually only results in frogs which are already
ill, are stressed or have weakened immune systems. Infected
frogs will usually develop cutaneous and visceral milliary
granulomas (white millet-like bumps) and ulcerative lesions on
the skin. Any of these mycobacteria can also gain entry to a
frog’s body through the skin wounds and lesions. Once through
the skin, these mycobacteria can also affect internal organs.
Mycobacterium
xenopi
is a slow-growing, waterborne, scotochromogenic species of
Mycobacterium. It was first isolated from skin lesions of
the frog, Xenopus laevis (Schwabacher, et al., 1959). The
organism is very resistant to most disinfectants used to clean
water systems and has been isolated in samples collected from
water systems in homes and hospitals.
Mycobacterium chelonae is a fast-growing, nontuberculous mycobacterial species. It
is a normal commensal in water and soil that can cause disease
in humans, fish and amphibians. Recently, this mycobacterium was
isolated from captive South African clawed frogs (Xenopus laevis)
showing chronic weight loss and nonhealing ulcerative skin
lesions (Green et al., 2000), and also from dolphin showing
pyogranulomas in blubber, as well as marked acute multifocal
necrosuppurative pneumonia and lymphadenitis (Wünschmann et al.,
2008).
M. chelonae
can cause a mortality rate of 90% in
infected immunocompromised human patients such as AIDS or cancer
patients. In humans, infection is usually via the pulmonary
route.
Mycobacterium liflandii infection of Xenopus tropicalis
can also result in coelomitis (infection of the coelom/abdomen)
and subsequent general or local edema (bloating). Cutaneous
lesions and bloating can occur independently. Once these signs
develop, the disease is consistently fatal and affected frogs
are usually euthanized.
Diagnosis of infections caused by mycobacteria, especially
nontuberculous mycobacteria, remains a difficult task both in
microbiology and pathology. Culture identification followed by
biochemical analysis is often slow and may not differentiate
pathogenic from nonpathogenic mycobacteria species due to their
close similarity. False positives occur in this way in both
staining and culture, particularly in environmental specimens.
Molecular detection by PCR, on the other hand, is a rapid,
sensitive and specific technique for sensitive mycobacterial
detection and differentiation.
This panel detects and
differentiates M. xenopi
and M. chelonae; it detects but does not differentiate the group
M. liflandii/M. ulcerans/M.
marinum, as these last three species are genetically
nearly identical.
Utilities:
-
Confirm the disease causing agent
-
Shorten the time required to confirm a clinical
diagnosis
-
Ensure that animal facilities or amphibian populations
are free of these mycobacteria
-
Early prevention of spread of these mycobacteria in a
facility or geographic area
-
Minimize human exposure to these mycobacteria
-
Safety monitoring of biological products that derive
from susceptible animals
References:
Schwabacher H. (1959) A strain of Mycobacterium isolated from
skin lesions of a cold blooded animal,
Xenopus laevus, and
its relation to atypical acid-fast bacilli occurring in man. J.
Hygiene, 57:57-67
Mve-Obiang, A., Lee, R.E., Umstot, E.S.,
Trott, K.A., Grammer, T.C.,
Parker, J.M.,
Ranger, B., Grainger, R., Mahrous, E.A. and Small, P.L.C. (2005)
A newly discovered mycobacterial pathogen isolated from lethal
infections in laboratory colonies of Xenopus species produces a
novel form of the M. ulcerans macrolide toxin, mycolactone.
Infect. and Immun. 73: 3307-3312.
Trott, K.A.,
Stacy, B.A., Lifland, B.D., Diggs, H.E., Harland, R.M., Khokha,
M.K., Grammer, T.C. and Parker, J.M. (2004) Characterization of
a Mycobacterium ulcerans-like infection in a colony of African
Tropical Clawed Frogs (Xenopus tropicalis) Comp. Med. 54:
309-317.
Green, S. L.,
Lifland, B. D., Bouley, D. M., Brown, B. A., Wallace, R. J., Jr.
and Ferrell, J. E., Jr. (2000) Disease attributed to
Mycobacterium chelonae
in South African clawed frogs (Xenopus
laevis). Comp. Med. 50: 675-679.
Wünschmann, A., Armien,
A., Beth Harris, N., Brown-Elliott, B.A., Wallace R.J., Jr.,
Rasmussen, J., Willette, M. and Wolf, T. (2008) Disseminated
Panniculitis in a Bottlenose Dolphin (Tursiops
truncatus) due to
Mycobacterium chelonae
Infection. J. Zoo Wildlife Med. 39: 412-420.
Specimen requirements:
Cloacal and
skin swab, or lesion swab, or skin scraping.
For specimen
types other than those listed here, please call to confirm
specimen acceptability and shipping instructions.
For all
specimen types, if there will be a delay in shipping, or during
very warm weather, refrigerate specimens until shipped and ship
with a cold pack unless more stringent shipping requirements are
specified. Frozen specimens should be shipped so as to remain
frozen in transit. See shipping
instructions for more information.
Turnaround time:
2 business days
Methodology:
Qualitative real time PCR panel
Normal range:
Nondetected
|
