Molecular biology in medicine: laboratory diagnosis of tuberculosis.

Clinical mycobacteriology has benefited much from the application of molecular biology techniques. Early detection and identification of Mycobacterium tuberculosis are achieved by the combined use of the BACTEC system and deoxyribonucleic acid (DNA) probes. High-performance liquid chromatography is the other alternative used in some laboratories. Polymerase chain reaction is still a research tool because of its many problems and limitations. Other promising techniques for rapid diagnosis of Mycobacterium tuberculosis, for example, the serological diagnosis by enzyme-linked immunosorbent assay (ELISA), the Gen-Probe Amplified Mycobacterium tuberculosis Direct Test, DNA hybridization, the Mycobacteria Growth Indicator Tubes System and the strand displacement amplification system are currently under evaluation. The discovery of drug resistant genes such as katG and apoB has important implications for the development of new tests for the rapid detection of resistance to anti-tuberculous drugs.