Identification of non-tuberculous mycobacteria by real-time PCR coupled with a high-resolution melting system.

Non-tuberculous mycobacteria (NTM) are increasingly important opportunistic pathogens responsible for a variety of clinical diseases. The aim of this study was to evaluate a novel technique, real-time PCR coupled with high-resolution melting analysis (real-time PCR-HRMA), for NTM identification. Two pairs of unique primers targeted to the 16S rRNA gene and the 16S-23S internal transcribed spacer region were selected for further evaluation. A total of 149 mycobacterial clinical isolates were subjected to analysis using the real-time PCR-HRMA system. Overall, 134 NTM identified by the 16S rRNA full-gene sequencing method were categorized into four major groups: Mycobacterium avium complex, Mycobacterium chelonae group, Mycobacterium gordonae and Mycobacterium fortuitum group. Of the 134 prevalent mycobacterial isolates, 101 mycobacteria (75.4 %) could be identified correctly by the real-time PCR-HRMA system. The individual sensitivities for the M. avium complex, M. chelonae group, M. gordonae and M. fortuitum groups were 90.9, 89.1, 100 and 36.8 %, respectively. The specificity of identifying these groups varied from 96.4 to 100 %. When identification failed, mostly it was attributable to various species in the M. fortuitum group. The real-time PCR-HRMA system is therefore a rapid and sensitive method for identifying prevalent NTM in a clinical laboratory.