Distribution of rpoB mutation in rifampin-resistant clinical Mycobacterium tuberculosis isolates from Shenzhen

Objectives:To investigate the distribution of rpoB mutation in rifampin resistant clinical Mycobacterium tuberculosis isolates from Shenzhen,and to develop a fast method for detecting M.tuberculosis drug resistance.Methods:280 bp DNA fragment of rpoB genes,including 75 bp code region(rifampin resistant determination region),were sequenced by using PCR direct sequencing (PCR DS) techniques.There were 55 strains of M tuberculosis clinical isolates including 51 rifampin resistant strains and 4 rifampin sensitive strains.Results:92 2%(47/51) rifampin resistant trains had rpoB mutation in 75 bp code region.No mutation was found in rifampin sensitive strains.41 2(21/51) rifampin resistant strains had mutations located at 531 Ser;29 4%(15/51)strains had mutations at 526 His;13 7%(7/51)strains had mutations at 516 Asp。Combinative mutation rate was 2 0%(1/51)。There were not deletion or insertion mutation found.Conclusions:531 Ser ,526 His and 516 Asp were the main positions of mutation.The added mutation rate was 84 3%(43/51) PCR DS techniques should be a fast and reliable identified test for rifampin resistance in clinical isolates.