Molecular techniques for the diagnosis of respiratory bacterial infection.

DNA amplification techniques are now available for all of the major respiratory bacterial pathogens. The most important recent developments have been in the application of these techniques to routine clinical practice. A major problem for rapid techniques is the need to provide susceptibility results. Effective susceptibility techniques have now been described for Streptococcus pneumoniae and Mycobacterium tuberculosis. It has also been possible to use amplification techniques to monitor the response to antituberculosis chemotherapy by monitoring mRNA in sputum samples. The added sensitivity the amplification-based techniques give over conventional culture techniques is valuable not only in enhancing diagnosis, which allows the use of less invasive specimens, but also in opening new investigative areas in the pathogenesis of respiratory conditions.