The purpose of this study is to provide a simple and reliable genetic typing approach for molecular drug susceptibility test of Mycobacterium tuberculosis, through the developing of fluorescence molecular marker of rifampicin resistance gene rpoB. Eleven fluorescent molecular markers of the rpoB gene were established by using the sequence difference between the amino acid positions 531, 526, 516, 511 and 513 of rpoB gene of rifampicin-resistant strains and the alleles of rifampicin-sensitive strains, combined with the PARMS technique (Penta-primer amplification refractory mutation system). We used 104 clinical isolates of Mycobacterium tuberculosis to validate this marker and it was verified by sequencing as 100% correct. These samples were also tested with proportional drug sensitivity test. The coincidence rate was 94.23%. The molecular markers had high reliability for genotyping of rpoB gene. It can also detect low-concentration drug-resistant samples (511/533 unit point mutations) whose phenotypic susceptibility cannot be detected. The eleven sets of fluorescent molecular markers could cover 92%-96% of rpoB gene mutation types of rifampicin-resistant strains, and provide new idea for rapid detection of rifampin-resistant Mycobacterium tuberculosis.
Keywords: Mycobacterium tuberculosis; PARMS technology; proportional drug sensitivity test; rifampicin resistance; rpoB gene.