Detection and identification of mycobacteria by amplification of a segment of the gene coding for the 32-kilodalton protein.

Abstract

A polymerase chain reaction (PCR) assay for the rapid detection of mycobacterial DNA is described. Oligonucleotide primers, derived from the sequence of a gene coding for the 32-kDa antigen of Mycobacterium tuberculosis, amplified DNA from all 28 species of mycobacteria tested. All nonmycobacterial species tested were negative. An oligonucleotide probe hybridized to the PCR products of the strains belonging to the M. tuberculosis complex. This method could detect as little as 50 fg, as tested with purified M. tuberculosis DNA. By this amplification method, 127 sputum specimens were tested, with 7.9% of the specimens proving to be inhibitory in PCR. The sensitivity of detection by PCR compared with that by culture was 55.9%; when the inhibitory specimens were excluded, the sensitivity was 70.4%. The specificity of PCR combined with hybridization was 100%.