Mycobacterium avium

Test codes:

B0029 - Ultrasensitive qualitative detection of Mycobacterium avium, subsp. avium by real time polymerase chain reaction. This assay does not detect subspecies paratuberculosis or other mycobacteria species.

B0030 - Ultrasensitive qualitative detection of Mycobacterium avium, subsp. paratuberculosis (Johne's disease) by real time polymerase chain reaction. This assay does not detect subspecies avium or other mycobacteria species.

Many different mycobacteria can cause disease in birds, mammals and reptiles. Infections occur through contact with other infected animals or humans through inhalation or the digestive route (Moreland, 1970). Infected animals can become reservoirs, causing outbreaks of disease. Mycobacterial infections have also been reported in many other captive and wildlife species.

Detection of mycobacterial infections has relied on tuberculin skin response, serological testing, histopathology, microscopy and culture identification. Among these, the most frequently used methods are culture identification and the tuberculin skin test (also known as the PPD, for Purified Protein Derivative), the latter being a routine test in quarantine and preventive medicine protocols (Fowler, 1993). However, the PPD test is not adequately sensitive or specific in many species and the rate of false negatives is high. Culture and associated biochemical tests for the identification of mycobacteria species are slow and painstaking procedures, and require careful collection and preservation of specimens in order to obtain accurate results.

PCR detection of mycobacterial DNA is highly sensitive when proper specimens are carefully collected. Sample types and collection techniques vary by species; deep respiratory samples obtained using bronchial lavage are preferred for some species. Gastric lavage can also be a useful sampling technique. Pathology samples should be taken from foci most likely to contain the pathogen -- typically lymph nodes or lung or other organ lesions. Trunk washes are used to obtain samples from elephants (National Tuberculosis Working Group for Zoo and Wildlife Species, 2003).

In addition to the detection of a number of mycobacterial species by real time PCR, identification of mycobacteria to the species level can be accomplished rapidly through sequence analysis of PCR products using a restriction fragment length polymorphism (RFLP) technique. Ultrasensitive detection of mycobacteria by PCR and subsequent restriction digest analysis not only allows reliable detection of various species of mycobacteria but in many cases also enables identification of mycobacteria at the species level.

Utilities:

• Confirm the disease causing agent
• Ensure that flocks are free of disease-causing mycobacteria
• Early prevention of spread of mycobacteria among a flock
• Minimize human exposure to disease-causing mycobacteria
• Safety monitoring of biological products and vaccines that derive from birds

References:
Brammer, D.W., O’Rourke, C.M., Heath, L.A., Chrisp, C.E., Peter, G.K. and Hofing, G.L. (1995) Mycobacterium kansaii infection in squirrel monkeys (Saimiri sciureus sciureus). J. Med. Primatol. 24: 231-235.
Calmette, A., Smith, G.H. and Soper, W.B.(1923) Tubercle Bacillus Infection and Tuberculosis in Man and Animals, Processes of Infection and Resistance, vol. Xxiii. Williams and Wilkins Company, Baltimore, 689 pp.
Fowler, M.E. (1993) Zoo & Animal Medicine: Current Therapy, 3rd ed., vol. xxv. Saunders, Philadelphia, 617 pp.
Moreland, A.F. (1970) Tuberculosis in New World primates. Lab. Anim. Care 20: 262-264.
Renquist, D.M. and Potkay, S. (1979) Mycobacterium scrofulaceum infection in Erythrocebus patas monkeys. Lab. Anim. Sci. 29: 97-101.
Smith, E.K., Hunt, R.D., Garcia, F.G., Fraser, C.E., Merkal, R.S., Karlson, A.G. (1973) Avian tuberculosis in monkeys. A unique mycobacterial infection. Am. Rev. Respir. Dis. 107: 469-471.
National Tuberculosis Working Group for Zoo and Wildlife Species (2003). Guidelines for the Control of Tuberculosis in Elephants. USDA-APHIS: http://www.aphis.usda.gov/ac/TBGuidelines2003.pdf

Preferred bird specimen: 0.5 ml fresh feces, shipped overnight at room temperature.

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

Normal range: Nondetected