POLYMERASE CHAIN-REACTION TO DETECT MYCOBACTERIUM-TUBERCULOSIS IN A CLINICAL MICROBIOLOGY LABORATORY

Direct detection of DNA from Mycobacterium tuberculosis in clinical specimens was performed by in vitro amplification of DNA using the polymerase chain reaction (PCR), followed by specific detection of the amplified product using DNA hybridization with a non-radioactive detection system. Primers based on a recently described insertion element IS986 were used to detect M. tuberculosis. The results were compared with results from traditional culture techniques. A total number of 107 specimens were examined. PCR and hybridization results were positive in 54 of 67 culture positive specimens. The number of PCR positive specimens was increased to 63 by concentrating the samples by ethanol precipitation prior to amplification. This treatment, however, decreased specificity. The negative PCR reaction in the remaining 4 culture positive samples could be explained by the presence of inhibitors. Of the 40 culture negative samples 5 were PCR positive, one of which was false positive. PCR and hybridization generated results significantly more rapidly than traditional culture techniques, but the former assay also appeared to be more expensive.