Molecular diagnosis of mycobacteria

Tuberculosis is one of the leading infectious diseases in the world and is responsible for more than 2 million deaths and 8 million new cases annually . Because of the slow growth rate of the causative agent Mycobacterium tube rculosis, isolation, identification, and drug susceptibility testing of thi s organism and other clinically important mycobacteria can take several wee ks or longer. During the past several years, many molecular methods have be en developed for direct detection, species identification, and drug suscept ibility testing of mycobacteria. These methods can potentially reduce the d iagnostic time from weeks to days. Currently two nucleic acid amplification methods, the Enhanced Mycobacterium tuberculosis Direct Test (Gen-Probe) a nd the Amylicor Mycobacterium tuberculosis Test (Roche Diagnostic Systems), have been approved by the Food and Drug Administration for direct detectio n of M. tuberculosis from clinical specimens. PCR-based sequencing has beco me commonly used to identify many mycobacterial species. DNA probes have be en widely used for species determination of the most commonly encountered m ycobacteria. High-density oligonucleotide arrays (DNA microarrays) also hav e been applied to simultaneous species identification and detection of muta tions that confer rifampin resistance in mycobacteria. (C) 2001 American As sociation for Clinical Chemistry