Genetic and phenotypic characterizations of drug-resistant Mycobacterium tuberculosis isolates in Cheonan, Korea.

BACKGROUND: Mycobacterium tuberculosis (MTB) causes tuberculosis (TB), which is a fatal disease. Cases of drug-resistant MTB have increased in recent years. In this study, we analyzed 7 sites of MTB DNA sequences, including the rpoB and inhA gene, to investigate the relationship between gene mutations and drug resistance in MTB.

METHODS: Mycobacterium tuberculosis liquid culture samples (197 specimens from 74 cases) were collected between June 2015 and May 2016 and sequenced. The results were compared with those obtained from antibiotic susceptibility tests.

RESULTS: In 65 (87.8%) cases, the antibiotic-resistant phenotype was consistent with genotyping results, whereas in 9 (12.2%) cases, there was no match. Eight mutations were detected in the rpoB gene, which showed the highest mutation rate. Sequencing results indicated that these mutations were present in 12 cases.

CONCLUSION: Previously published data on antibiotic resistance genes are insufficient for effective prevention of multidrug- or extensive drug-resistant TB. Additional studies are needed to characterize the complement of antibiotic resistance genes in MTB.