[Progress in clinical microbiology of Mycobacterium avium complex and prospect on its future]

Recent advance of technology in isolation and identification methods for mycobacteria, including BACTEC 460 TB System, polymerase chain reaction (PCR), DNA probe test, etc., enabled us to perform rapid and accurate identification of mycobacterial pathogens from various clinical specimens. Our recent study revealed usefulness of BACTEC 460 TB System, on the basis of the high efficiency in detecting the organisms in sputum specimens with much shortened recovery time, as compared to the Ogawa method. Moreover, accurate identification was possible, when the diagnostic system was combined with AccuProbe test. PCR using appropriate primers specific to Mycobacterium, M. tuberculosis complex (MTC), or M. avium complex (MAC) is useful to detect mycobacterial organisms directly in clinical specimens in a rapid manner. By this technique, in particular nested PCR, it is now possible to detect very small number of the organisms, as few as one bacterium, in test specimen, although it is still needed to resolve some difficulties due to contaminating inhibitors in the specimens. In our nested PCR system using Mav17 and Mav18 primers specific for Mycobacterium, especially MAC, we found that detectable degree of DNA amplification was possible even by replacing purified DNA sample, extracted from the organisms by considerably time consuming procedures, with bacterial suspension as a DNA template, by adding about 10(4) of organisms. The three DNA probe testings, Gen-Probe, AccuProbe and SNAP kits, are useful for rapid identification of MAC, MTC, M. kansasii and M. gordonae, and consistent results were obtained by these diagnostic kits. SNAP is able to distinguish the X component of MAC from the other two types of MAC.(ABSTRACT TRUNCATED AT 250 WORDS)