Molecular analysis on relations between rpoB gene mutations and rifampin resistance in Mycobaoterium tuberoulosis from Guangdong

Objective To study the characteristics of rpoB gene mutations of Mycobacterium tuberculosis in Guangdong province. Methods The drug susceptibility profiles were evaluated by absolute concentration method and genetic mutations on rpoB gene were identified by DNA direct sequencing. Results In our study, 27 rifampin resistant were found, M. tuberculosis were obtained, including 8 low level resistant isolates and 19 high level resistant isolates, All of the rifampin susceptible isolates were found to harbor no detectable mutations. 81.5% of rifampinresistant strains were found to have mutations in the analyzed pro B,which located at codon 526, 531 and533, and the most frequent mutation pattern was Ser531Leu (55.6%).The frequency of rpoB mutations of high level resistant isolates was higher than those of low level resistant isolates. Conclusion In conclusions, mutations of rpoB gene were the main molecular mechanism of rifampin resistant M. tuberculosis. The mutation sites of rifampin resistant strains correspond with current studies, but the proportion of each mutation form has their own characteristics in our study. Key words: M. tuberculosis;  Resistance;  RpoB gene;  Mutations analysis