Drug-resistant tuberculosis: resistance mechanisms and rapid susceptibility testing.

Globally, the emergence of multidrug-resistant strains of Mycobacterium tuberculosis is an increasing problem which adversely affects patient care and public health. In contrast to other bacteria, resistance of M. tuberculosis is exclusively associated with chromosomal mutations. Recently developed molecular biological techniques have significantly helped in understanding the basis of drug action and resistance mechanisms in this organism. The information gained at the molecular level will help to develop efficient future diagnostic strategies and create novel drugs, both of which will ultimately have a direct impact on treatment programmes.