[Characterization of rpoB mutation in rifampin - resistant clinical Mycobacterium tuberculosis isolates from China]

To elucidate the characterization of rpoB mutation in rifampin - resistant clinical isolates of Mycobacterium tuberculosis isolates from China.

588 bp DNA fragment of rpoB gene including 81 bp code region (rifampin resistance determination region, RRDR) was sequenced. 242 strains of Mycobacterium tuberculosis, including 193 rifampin - resistant strains and 46 rifampin - susceptible strains and 3 artificially induced rifampin - resistant strains were sequenced.

89.1% (172/193) rifampin - resistant strains had rpoB gene mutations in RRDR, no mutation was found in rifampin - susceptible strains. 46.1% rifampin - resistant strains had mutations located at 531-Ser; 17.1% strains had mutations located at 526-His; Combinative mutation rate was 12.4%; 4 strains had synonymous mutations; No deletion or insertion mutation was found among all strains. High level rifampin resistant strains (250 microgram/ml rifampin resistant) had higher mutation frequency at 531 - Ser than low level rifampin resistant strains (50 microgram/ml rifampin resistant) (P < 0.05).

About 90% rifampin resistant clinical strains of Mycobacterium tuberculosis from China had rpoB mutations; 531-Ser and 526 - His were the most common positions to be substituted, the added mutation rate was about 46%; High level rifampin resistant strains had a higher frequency of 531-Ser mutation than low level rifampin resistant strains; No insertion or deletion mutation was found in these specimens; DNA sequencing is significant in drug choosing for tuberculosis treatment.