Sequence analysis on drug-resistant rpoB gene of Mycobacterium tuberculosis L-form of isolated from pneumoconiosis workers

Objective:To study the characteristics of drug-resistant genetic mutation of rpoB on coal workers' pneumoconiosis complicated with L-form of Mycobacterium tuberculosis. Methods: A total of 42 clinical isolated strains of Mycobacterium tuberculosis L-forms were collected, including 31 drug-resistant strains. 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. Results: No mutation of rpoB gene was identified in 11 rifampicin-sensitive strains while conformation changes were found in 31 rifampicin-resistant strains. The mutation rate was 93.55% (29/31) in resistant strains, mainly concentrated in codon 531 (51.6%, 16/31) and 526 (32.26%, 10/31). Base substitutions happened, including 27 unit point mutation and 2 two point mutation. The mutation of codon 516 that new found wasn't reported by internal and overseas scholars. Conclusion: The substitution of highly conserved amino acids encoded by rpoB gene results in the molecular mechanism responsible for rifampicin resistance in Mycobacterium tuberculosis L-forms. It also proves that rpoB gene is diversiform.

To study the characteristics of drug-resistant genetic mutation of rpoB on coal workers＇ pneumoconiosis complicated with L-form of Mycobacterium tuberculosis. Methods： A total of 42 clinical isolated strains of Mycobacterium tuberculosis L-forms were collected, including 31 drug-resistant strains. 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. Results： No mutation of rpoB gene was identified in 11 rifampicin-sensitive strains while conformation changes were found in 31 rifampicin-resistant strains. The mutation rate was 93.55% （29/31） in resistant strains, mainly concentrated in codon 531 （51.6%, 16/31） and 526 （32.26%, 10/31）. Base substitutions happened, including 27 unit point mutation and 2 two point mutation. The mutation of codon 516 that new found wasn＇t reported by internal and overseas scholars. Conclusion： The substitution of highly conserved amino acids encoded by rpoB gene results in the molecular mechanism responsible for rifampicin resistance in Mycobacterium tuberculosis L-forms. It also proves that rpoB gene is diversiform.