Abstract
The drug-resistant profile of tuberculosis (TB) varies across geological regions. This study aimed to evaluate the association of katG, inhA, and AhpC mutations with isoniazid (INH) resistance of Mycobacterium tuberculosis in pulmonary TB patients from Nanjing, China. Laboratory and genetic data of INH-resistant genes in TB patients living in Nanjing and hospitalized in the Department of Tuberculosis, the Second Hospital of Nanjing, from January 2019 to December 2021 were retrospectively analyzed. A total of 1,712 human M. tuberculosis strains (1,308 INH-sensitive and 404 INH-resistant) were identified by phenotypic drug susceptibility testing (DST). Mutations were detected in katG315, the inhA promoter region, and the AhpC promoter region. Among the 172 INH-resistant strains identified by phenotypic DST, 159 samples of gene mutations were detected. The mutation rate in katG315 in INH-resistant strains was significantly higher than those in the inhA promoter region and AhpC promoter region. The rate of INH resistance was higher in M. tuberculosis strains with the katG315 mutation combined with the inhA/AhpC promoter region mutations than in those with a single mutation in katG315. The incidence of the katG315 mutation in multidrug-resistant TB patients and pre-extensively drug-resistant (pre XDR) TB patients was significantly higher than that in INH-resistant TB patients. The rate of katG315 mutation combined with the inhA/AhpC promoter region mutation was higher in pre XDR-TB patients. The katG315 mutation, or its combination with inhA/AhpC promoter region mutations, may be the main cause of INH resistance of M. tuberculosis strains in TB patients from Nanjing, China.
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