Published: July 28th, 2015
Revised: March 23rd, 2017
Tuberculosis (TB) is caused by the bacterium Mycobacterium tuberculosis. The M. tuberculosis complex (MTBC) includes four other Tuberculosis-causing mycobacteria: M. bovis, M. africanum, M. canetti, and M. microti. The bacteria usually attack the lungs, but TB bacteria can attack any part of the body such as the kidney, spine, and brain. By contrast, non-tuberculous mycobacteria (NTM) are common inhabitants of the environment and have been cultured from water, soil, and animal sources worldwide. NTM are opportunistic pathogens, mostly affecting patients with pre-existing pulmonary disease such as chronic obstructive pulmonary disease or tuberculous, or those with systemic impairment of immunity. The latter group includes individuals with HIV, Leukemia and those using immunosuppressive drugs. Mycobacterium chimaera is one such NTM that has been identified to have caused respiratory tract infection in patients with cystic fibrosis.1,2 Culture based analytical techniques are very useful for the identification of NTM, but have the limitation of taking up four weeks for results. The development of Polymerase Chain Reaction (PCR) based tests specific for mycobacteria has decreased testing time from several weeks to several hours by allowing the direct detection of mycobacteria from mixed samples without the need for culturing.
This test detects NTM using PCR. Real-time PCR (RT-PCR) is a rapid and accurate tool for the detection of NTM. It is important to note that this method cannot distinguish between living and dead cellular material. Analytical results will be reported as positive or negative for NTM DNA. A negative result does not necessarily refute the presence of potentially infectious material in the area tested, since only a small amount of material is subjected to the test. The testing of multiple replicate samples is helpful to establish confidence on the generalizability of results. A positive result, however, may provide information that is useful in public health interventions.
1 Sorin Group Important Information Cardiac Surgery Mycobacterium Risks, Disinfection and Cleaning of Sorin Heater Cooler Devices. July 14, 2014. Ref. No. IIS 9611109-07-14-14
2 Cohen-Bacrie et al. Journal of Medical Case Reports 2011, 5:473.