Evaluation of Q Gene Mycobacteria: A novel and easy nucleic acid chromatography method for mycobacterial species identification

Objectives: A simple, rapid, and new diagnostic test for mycobacteria, named Q Gene Mycobacteria, has been developed. It is based on multiplex PCR using primers harbouring DNA tags combined with a dipstick nucleic acid chromatography method, which does not require the denaturation of PCR products for hybridization and can identify five species of mycobacteria including Mycobacterium tuberculosis complex (MTC), Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium kansasii, and Mycobacterium gordonae. This study aimed to evaluate Q Gene Mycobacteria for the accurate identification of these five species. Methods: A total of 340 mycobacterial strains/isolates were tested, of which 159 were type strains (four MTC and 155 non-tuberculosis mycobacteria (NTM) including four subspecies) and 181 were clinical isolates (18M. tuberculosis, two Mycobacterium bovis Bacillus Calmette et Guerin (BCG), and 161 NTM comprising 16 species) collected from eight laboratories and hospitals in Japan. Species identification of NTM isolates was performed using the DNA-DNA hybridization method and/or direct sequencing of 16S rRNA, hsp65, and rpoB genes. Q Gene Mycobacteria was compared with above conventional methods for identifying the five species. Results: Q Gene Mycobacteria showed excellent concordance for species identification, specifically 99.4% (158/159) for type strains and 99.4% (180/181) for clinical isolates. The two strains that were misidentified as M. gordonae were Mycobacterium paragordonae. As they are genetically close and there is few case reports of M. paragordonae, it might not be a serious critical issue to distinguish M. paragordonae from M. gordonae. Conclusions: Q Gene Mycobacteria was able to identify frequently isolated mycobacterial species accurately and easily. Therefore, Q Gene Mycobacteria could be a useful tool for the identification of specific mycobacteria in clinical laboratories.