Genetic and Virulence Characteristics of Linezolid and Pretomanid Dual Drug-Resistant Strains Induced from Mycobacterium tuberculosis in vitro

摘要

Purpose: Linezolid (LZD) and pretomanid (PA-824) are promising candidates in regimens for the treatment of drug-resistant tuberculosis. However, research on LZD and PA-824 dual drug-resistant (LPDR) strains is rarely reported. This study aimed to investigate the genotypic and virulence characteristics of LPDR strains. Methods: To obtain the LPDR strains (marked as LP or PL strains), we used a two-way induction method, namely, we first induced LZD- or PA-824-resistant mutants from the parental Mycobacterium tuberculosis (MTB) strain H37Rv in vitro, then we obtained the LPDR strains from induction of LZD- or PA-824-resistant mutants. Mutations in rplC, rrl , or ddn and fgd1 were identified in all mutants. To investigate the virulence of these strains, six strains were selected as representative strains, including LZD-resistant strains, PA-824-resistant strains and LPDR strains. We performed the animal survival study as virulence of MTB can be measured as survival time of an animal after being infected. Results: We induced 38 mutant strains of LZD and PA-824 mono or dual drug resistance from H37Rv in vitro. The mutation frequency of rplC (C154R) gene in LPDR strains was 100% and 86%, respectively. In the animal survival study, animals infected with different drug-resistant strains survived significantly longer than those infected with H37Rv; animals infected with LPDR strains and PA-824-resistant strains survived similarly and both of which survived significantly shorter than those infected with LZD-resistant strains. Conclusion: Our study showed that rplC gene had a high mutation frequency in LPDR strains. The virulence of LPDR strains was similar to PA-824-resistant strains, and the virulence of the LZD-resistant strains was weaker than PA-824-resistant strains.