Identification of mycobacteria by PCR-based sequence determination of the 32-kilodalton protein gene

In this study, a part of the nucleotide sequence of the mycobacterial 32-kDa protein gene was determined by PCR-based sequencing. A total of 24 mycobacterial strains, representing 10 species, were studied. Sequences of all tested members of the Mycobacterium tuberculosis complex were identical to each other and to the previously published sequence of M. tuberculosis H37Rv. The sequences of M. avium and M. intracellulare were different from each other. MAIX strains, identified with the Gen-Probe MAIX test, had sequences identical to each other but clearly different from those of M. avium and M. intracellulare. Each of the other mycobacterial species investigated, i.e., M. kansasii, M. gastri, M. gordonae, and M. malmoense, had a unique species-specific sequence. These results demonstrate that there is variation in the nucleotide sequence of the 32-kDa protein gene among different mycobacterial species. Thus, we propose that this gene can be used for PCR-based identification of mycobacteria.