Aims: To facilitate efficient identification of commonly encountered mycobacteria species (Mycobacterium tuberculosis, Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium fortuitum complex, Mycobacterium chelonae/abscessus, Mycobacterium kansasii, Mycobacterium gordonae) in high throughput laboratories, a 16s rDNA sequence based real-time PCR assay was developed and evaluated.
Methods and results: Oligonucleotide primers and hybridization probes were designed based on sequence differences of the mycobacterial 16S rDNA gene. This assay was evaluated with 1649 suspected non-tuberculosis mycobacterial isolates. Apart from 3 out of 40 M. avium isolates that showed false signal with M. intracellulare specific probe, 100% specificity was obtained for all tested probes. Assay sensitivity varied from 88.9 to 100% depending on species. Average cost for obtaining a definite identification was only USD 1.1 with an average turn around time of less than 3 days.
Conclusions: A rapid, simple and inexpensive real-time PCR assay was developed for the identification of common encountered mycobacteria in a high throughput laboratory setting.
Significance and impact of the study: With this assay, more than 80% of the clinically isolated nontuberculous mycobacteria could be identified in a highly cost effective manner. This helped to save resources for other laboratory activities especially in high throughput mycobacterial laboratories.