Mutations related to rifampicin and isoniazid resistance in Mycobacterium tuberculosis strains in Ankara, Turkey

The identification of mutations associated with drug resistance is of paramount importance for the rapid detection of drug-resistant Mycobacterium tuberculosis strains. The objective of this study was to identify the mutations responsible for conferring resistance to rifampicin (RIF) and isoniazid (INH) in M. tuberculosis. A total of 84 drug-resistant M. tuberculosis strains including 41 multidrug-resistant (MDR) strains, 37 INH-resistant, RIF-susceptible strains, and 6 RIF-resistant, INH-susceptible strains were analyzed. The 86 M. tuberculosis strains were isolated from clinical samples, between 2022 and 2023 in Ankara, Turkey. PCR amplification and sequencing of rpoB, katG and inhA genes were performed to detect mutations. In the 47 RIF-resistant strains, the predominant mutation in rpoB was S450L observed in 40 of 47 strains (85%), followed by H445Y detected in two strains (4.3%). The Q432K/P, M434I, D435Y, T444I, H445G, S450W, and S450F mutations were identified in one strain each. The S315T mutation in the katG gene was identified in 60 of the 78 INH-resistant strains (76.9%). The rate of mutation -15C>T in inhA was 29.5% (23/78). Both S315Y and -15C>T mutations were detected in six strains (7.7%). This study provided comprehensive information regarding the genetic background of drug-resistant tuberculosis in terms of prevalent mutations responsible for RIF and INH resistance. These findings contribute to develop more sensitive qPCR tests that target mutations for the rapid detection of drug-resistant TB.