Objective To study the drug-resistant characteristics genetic mutation of rpoB in Mycobacterium tuberculosis L-forms among patients of pneumoconiosis complicated with pulmonary 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 and target genes amplified by PCR. Hot regions in the rpoB gene were analyzed by automated DNA sequenator. Results No mutation of rpoB was identified in 11 rifampicin-sensitive strains while conformation changes were fotmd 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), happened base substitutions, including 27 unit point mutation and 2 two point mutation. The newly found mutation of codon 516 had not been reported by internal or overseas scholars. Conclusion The substitution of highly conserved amino acids encoded by rpoB gene resulted in the molecular mechanism was responsible for RFP resistance in Mycobacterium tuberculosis L-forms. It also proved that rpoB gene was in diversiform.%目的 探讨淮南矿区尘肺结核患者感染结核分枝杆菌L型利福平耐药基因rpoB突变特点.方法 收集结核分枝杆菌L型临床分离株42株,其中利福平耐药株31株,敏感株11株,抽提临床分离株DNA和H37Rv标准菌株DNA,PCR法扩增rpoB基因,并应用全自动DNA测序仪对rpoB基因的突变集中区域进行测序分析.结果 42株结核分枝杆菌L型中,31株耐药株rpoB基因突变率93.55%(29/31),主要集中在531位点(51.61%,16/31)和526位点(32.26%,10/31)碱基置换突变,新发现516位点突变目前在国内外研究中未见报道.11株敏感株未见rpoB基因单链构象异常.结论 高度保守的rpoB基因突变是导致结核分枝杆菌L型利福平耐药的分子基础,其突变位点呈多样性.
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