Title: Study of mutations associated with isoniazid resistance in clinical Mycobacterium tuberculosis strains from Tehran and Isfahan province tuberculosis centers by PCR and RFLP(1383–4)
Abstract:Background: Although isoniazid is most efficient in killing the tuberculosis bacilli, resistance to this drug also develops most readily. Mutations in katG, inhA and ahpC are responsible for isoniazid...Background: Although isoniazid is most efficient in killing the tuberculosis bacilli, resistance to this drug also develops most readily. Mutations in katG, inhA and ahpC are responsible for isoniazid resistance in a large proportion of tuberculosis cases. However, the frequency of these mutations varies with population samples. This study provided the first molecular characterization of isoniazid resistance of M. tuberculosis strains that is widely applicable for rapid drug resistance detection. Methods: The study was diagnostic-testing and presence of mutations in specific regions of the katG, inhA and ahpC genes was analyzed with 32 M.tuberculosis isoniazid-resistant strains from Isfahan and Tehran. The katG mutations in codon 315 associated with isoniazid resistance among isoniazid resistant isolates was determined by PCR-RFLP. In this way, 355 bp PCR products were digested by MspI and MspA1I. Mutations in inhA and ahpC genes were detected by sequencing Results: Mutations in the katG 315(Ser→Thr), inhA and ahpC were detected in 71.9, 18.9 and 6.2% of the 32 isoniazid resistant isolates, respectively. Mutations were not found in one (%) of the isolates. Discussion: The PCR-RFLP with MspI that detect katG Ser315Thr substitution identified more isoniazid-resistant strains with mutations at codon 315 in the katG. Elucidation of the molecular basis of isoniazid resistance in M. tuberculosis has led to the development of different genotypic approaches for the rapid detection of isoniazid resistance in clinical isolates. The results also suggest that detection of the Ser315Thr in the katG gene may be used as a rapid screening method for identifying isoniazid-resistant clinical M. tuberculosis isolates recovered from Isfahan and Tehran tuberculosis centers.Read More