Rapid diagnosis of Mycobacterium tuberculosis infections by an ELISA-like detection of polymerase chain reaction products.

A polymerase chain reaction (PCR) assay was developed for the detection in clinical samples of mycobacteria belonging to the Mycobacterium tuberculosis complex. PCR products were detected with a simple and rapid colormetric method. With this method, 50 fg of M. tuberculosis DNA were detectable with the repetitive DNA-sequence-derived primers, corresponding to 10 genome equivalents. Detection of M. tuberculosis in 258 clinical samples by PCR was compared with detection by culture. PCR was positive for 56 of 57 culture-positive and Ziehl-Neelsen-staining-positive (ZN) samples, 11 of 18 culture-positive and ZN-negative samples. The presence of groEL DNA sequences was also investigated by PCR for all the specimens with the same revelation protocol. Three of the eight false-negative samples with the repetitive element-derived primers were found to contain groEL DNA sequences specific for the Mycobacterium genus. Among the 183 culture-negative samples, 30 were positive by PCR. When clinical data were known, the diagnosis of tuberculosis was established for the patients from whom those samples had been obtained. The results show that the rapid and simplified PCR assay described here is slightly more sensitive than culture and can be used in routine clinical practice.