Value of polymerase chain reaction (PCR) in diagnosis of tuberculosis and mycobacterium infections caused by ubiquitous mycobacteria

: The rise in both incidence and the number of multi-drug-resistant strains has made tuberculosis an alarming health problem even in some developed countries. Moreover, due to the HIV pandemic an increase in mycobacterial diseases caused by ubiquitous mycobacteria has been observed. The microbiological standard procedures are critical diagnostic tools, and a more rapid detection of mycobacteria by new laboratory techniques would be helpful. We investigated the role of the polymerase chain reaction (PCR) in the detection of M. tuberculosis complex and of ubiquitous mycobacteria. 580 clinical specimens obtained from 525 patients were examined. The majority of sampled material was bronchoalveolar lavage fluid. Based on cultural identification of mycobacteria, the incidence of tuberculosis in our patients was 3.4%. For detection of M. tuberculosis complex the insertion sequence IS 6110 was used. Relative to cultural identification, diagnostic specificity of PCR was 99.5%, and sensitivity was 66.7%, respectively. In 3.0% of the total patient group and in 8.8% of HIV-infected patients an infection by ubiquitous mycobacteria was found. Ubiquitous mycobacteria were detected using the hypervariable region of the 16S-rRNA-gene, and species-identification was done by sequence analysis. For ubiquitous mycobacteria, sensitivity of PCR was 60.0% relative to cultural identification and 62.5% relative to a proven disease. PCR is a useful method in the rapid diagnosis of pulmonary tuberculosis with excellent specificity but lack of sensitivity.