[Recent advances in diagnostic microbiology for mycobacterial infections]

Definitive diagnosis of tuberculosis continues to depend on microscopy and culture. Since routine diagnostic methods are insensitive and time-consuming (3 to 8 weeks), the development of more sensitive and rapid tests is desirable. More sensitive liquid media, radiometric BACTEC system and nonradiometric Septi-Chek AFB system are currently used in clinical laboratories. Advances in DNA techniques have provided a new approach to rapid diagnosis of mycobacterial diseases. Species-specific DNA probes for identifying Mycobacterium tuberculosis complex, M. avium, M. intracellulare, M. kansasii, and M. gordonae from cultures of acid-fast microorganisms are now commercially available. Amplification techniques such as polymerase chain reaction (PCR) provide rapid methods for detecting mycobacterial DNA or RNA directly from clinical samples. Two amplification kits, an rRNA amplification-based Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test system and a PCR-based Roche AMPLICOR MYCOBACTERIUM system, are commercially available. These systems have the speed, reliability and requisite diagnostic capability for detecting mycobacteria directly from clinical specimens.