[Rapid detection and identification of mycobacteria by the PCR assay based on the co-amplification of the gene IS6110 and groEL].

In definite diagnosis of mycobacterial infection, prompt and adequate differential diagnosis leads to an appropriate treatment. We developed and evaluated a PCR assay based on co-amplification of the insertion sequence IS6110 and groEL gene that are species-specific for Mycobacterium tuberculosis complex and genus-specific, respectively. The detection limit of the assay system for cultured M. tuberculosis was 2 cells/ml, as compared with 200 cells/ml by culture onto Ogawa's medium. To assess the value of the assay in routine laboratory works, the results obtained by PCR were compared with those by standard microbiological methods for 758 specimens collected for the examinations of mycobacterial infection. The PCR system for detection of mycobacteria gave overall positive rate of 27.6% (209/758), as compared to 6.1% (46/758) by smear and 7.7% (58/758) by culture onto Ogawa's medium. Sensitivity and specificity were 97.8% and 97.3%, respectively, for the IS6110 and groEL gene for detection of M. tuberculosis complex; 91.7% and 80.3%, respectively, for only the groEL gene for detection of atypical mycobacteria. The PCR assay based on co-amplification of the IS6110 and groEL gene would be useful for diagnosis of mycobacterial infections, allowing not only more sensitive detection of mycobacteria but also rapid discrimination between M. tuberculosis complex and atypical mycobacteria. This assay would help to eliminate time-consuming confirmation, and to avoid both unnecessary treatment and hospitalization of the patient.