Establishment of Chinese reference strains for in vitro drug sensitivity testing of Mycobacterium tuberculosis

Objective To establish Chinese reference strains for in vitro antimicrobial susceptibility testing of Mycobacterium tuberculosis in China by systematically identification and evaluation of 5 Chinese clinical Mycobacterium tuberculosis strains that have been used for many years in accordance with the Technical Requirements forEvaluation of National Standard Strains of Pathogenic Microorganisms(WS/T 812—2022).

Methods Standard operation procedure was established. Bacterial culture characteristics, phenotype characteristics, biochemical tests, antimicrobial susceptibility testing, and molecular feature were systematically evaluated. Whole genome sequencing was conducted, and library of main and working strains were established.

Results The phenotypic, biochemical, and molecular biological results of the five strains showed that the characteristics of these bacteria were stable and consistent with that of Mycobacterium tuberculosis, which were composed of 2 pan-susceptible strains, 2 multi-drug resistant tuberculosis strains, and 1 extensively drug resistant tuberculosis strains. Whole genome sequencings were completed for all strains. National preservation number and standard strain certificate were obtained from National Pathogen Resource Center.

Conclusion The characteristics of the five strains meet the requirements of quality control strains for in vitro drug susceptibility testing of Mycobacterium tuberculosis and strains for anti-tuberculosis drug screening and evaluation. It will provide guideline for the establishment of Mycobacterium tuberculosiscomplex reference strains, and strong support for drug resistance monitoring of tuberculosis and anti-tuberculosis drug research in China.