OBJECTIVETo study the characteristics of drug-resistant genetic mutation of rpoB in multiple drugs resistant bacillus tuberculosis (MDR-TB) among patients of pneumoconiosis complicated with pulmonary tuberculosis.

METHODSA total of 114 clinical isolated strains of Mycobacterium tuberculosis were collected, MDR-TB were identified by conventional antimicrobial susceptibility test (AST). Their genomes DNA were extracted, the target genes were amplified by PCR, and the hot regions in the rpoB gene were analyzed by automated DNA sequenator.

RESULTSThe results by AST showed that there were 31 strains of MDR-TB in the 114 clinical isolated strains, the rate of drug resistance was 27.19% (31/114). No mutation of rpoB was identified in 10 rifampicin-sensitive strains that randomly chosen, while conformation changes were found in MDR-TB strains, and the mutation rate of rpoB was 93.55% (29/31) in resistant strains, mainly concentrated in codon 531 (45.16%, 14/31) and 526 (29.03%, 9/31), happened base substitutions, including 27 unit point mutation and 2 two point mutation.

CONCLUSIONSThe substitution of highly conserved amino acids encoded by rpoB gene results in the molecular mechanism responsible for RFP resistance in MDR-TB among patients of pneumoconiosis complicated with pulmonary tuberculosis. It also proves that rpoB gene is diversiform.