Mechanisms of drug resistance in Mycobacterium tuberculosis and current status of rapid molecular diagnostic testing.

Drug-resistant tuberculosis has become a global problem and a major public health concern. While mechanisms of resistance are fairly well characterized for most agents, particularly the first line agents, our knowledge of drug resistance is by no means exhaustive, and strains continue to emerge that carry novel resistance-related mutations. The purpose of this review is to summarize our current understanding of the genetic basis of drug resistance in Mycobacterium tuberculosis, highlighting emerging areas of research. The development of rapid detection methods has been a major breakthrough in the fight against drug-resistant tuberculosis. Rapid detection methods are available for both rifampin- and isoniazid-resistant tuberculosis, but have yet to be developed for other first line agents. Rapid detection methods will become increasingly important as multi-drug resistant strains of M. tuberculosis become more prevalent, even for detecting tuberculosis that is resistant to second line agents.