Molecular mutations of rpoB gene of multidrug resistant Mycobacterium tuberculosis isolates from China

To characterize rpoB mutations of multidrug resistant Mycobacterium tuberculosis clinical isolates from China, mutations in the 81 bp rifampin resistance determining region (RRDR) and mutation V176F locating in the beginning of the rpoB gene were analyzed by DNA sequencing. Eighty six Mycobacterium tuberculosis clinical isolates, including 72 rifampin resistant strains and 14 rifampin sensitive strains were sequenced. Six five mutations of 22 distinct kinds, 21 point mutations and one insertion, were observed in 65 of 72 resistant isolates. The most frequent mutations were in codon 531 (41%), 526 (40%), and 516 (4%). Mutations were not found in seven (10%) of the resistant isolates. Six new alleles within the RRDR, along with five novel mutations outside the RRDR, are reported. None of isolates contained the V176 mutation.