Characterization and rapid detection of mutations in RpoB gene of rifampin-resistant mycobacterium tuberculosis strains

Purpose: To elucidate the characterization of rpob mutations in rifampin-resistant clinical myocobacterium tuberculosis isolates from Shanghai, and explore the significance of DNA sequencing of rpoB gene in the diagnosis of M. tuberculosis resistance to rifampin. Methods: 58 isolates of M. tuberculosis including 36 rifampin resistant strains and 22 susceptible strains were studied. A fragment(213 bp) of rpoB gene of all of the 58 isolates was amplified and sequenced, which comprise the 69 bp rifampin resistance determination region. Results: All of the 36 rifampin-resistant isolates had mutation in the 69 bp region of rpoB gene, and there were no mutations in any of the susceptible strains. The mutation of 531-Ser and 526-His contributed to 47.2% and 25.0% respectively of all the mutations. Conclusions: Mutations in the 69 bp hypervariable region of rpoB are the main reason of M. tuberculosis resistant to rifampin. 531-Ser and 526-His are the most common positions of mutations.