Abstract:

Objective To compare microarray chip and multiple homologous sequence in the identification of non-tuberculous Mycobacterium（NTM），and to provide accurate diagnosis reference for the clinical diagnosis and treatment of NTM infection. Methods For preserved NTM from 2016 to 2019 in Tianjin Haihe Hospital，using microarray chip and multiple homologous sequence，including 16S rRNA，subunit of RNA polymerase B（rpoB），heat shock protein 65（hsp65），the 170 isolates of NTM were analyzed. The accuracy of microarray chip was analyzed for NTM using the identification results of multiple homologous sequence as reference method. The turn-around times（TAT） were compared between the 2 methods. Results Totally，8 NTM species were identified by microarray chip，and 14 NTM species were identified by multiple homologous sequence. Microarray chip failed to identify 10 isolates of slowly growing Mycobacteria（Mycobacterium simiae，Mycobacterium lentflavum and Mycobacterium parascrofulaceu） and rapidly growing Mycobacteria（Mycobacterium chelonae，Mycobacterium mageritense and Mycobacterium vaccae）. All the isolates could be identified by multiple homologous sequence. Based on the results of multiple homologous sequence，7 errors were identified by microarray chip，and the identification accuracy of complex groups was 90.0%（153/170）. The accuracies of 16S rRNA，rpoB，hsp65 and 3 homologous sequences were 93.5%，98.8%，99.4% and 100.0%，respectively. For 53 isolates of Mycobacterium chelonis/Mycobacterium abscessus complex（MABC） that could not be distinguished by microarray chip，6 isolates of Mycobacterium chelonis，25 isolates of MABC subspecies，20 isolates of MABC Masai subspecies and 2 isolates of MABC bolletii subspecies were identified by 3 homologous sequences. It took 8 h for TAT to be identified by microarray chip and 2 d for all the 170 NTM isolates to be identified. It took 3 d to identify TAT from a single sample by multiple homologous sequence and about 5 d to identify all the 170 NTM isolates. Conclusions Microarray chip could quickly provide accurate results for clinical identification of common Mycobacterium species. Multiple homologous sequence could not only identify common Mycobacterium species，but also could provide more accurate identification results and subspecies for the isolates that can not be identified by microarray chip.

Key words: Microarray chip, Homologous sequence, Non-tuberculous Mycobacterium, Mycobacterium abscessus complex, Turn-around time