Investigation of Drug Resistant Mycobacterium tuberculosis Strains with Molecular Methods

The aim of this study was to investigate mutations in the rpoB and embB genes using molecular methods in Mycobacterium tuberculosis isolates phenotypically resistant to rifampicin and/or ethambutol. Drug susceptibility testing of 110 isolates collected in Turkey between 2005 and 2014 was performed using the modified agar proportion method. Molecular analysis was conducted on 28 selected isolates, including 7 rifampicin-resistant strains. Mutations were detected within the Rifampicin Resistance-Determining Region (RRDR) between codons 507–533 of the rpoB gene. The most common mutation was Ser531Leu (TCG→TTG), found in 10 strains; one strain had a His526Asn (CAC→AAC) mutation. These mutations were considered important molecular markers of rifampicin resistance. Rapid molecular detection of these mutations is important for early and effective tuberculosis treatment planning.