对利福平耐药的结核分枝杆菌rpoB基因突变与耐药程度关系的探讨

Mutation of DNA fragment of rpoB gene in different degrees of rifampin-resistance in Mycobacterium tuberculosis.

目的 探讨对利福平耐药结核分枝杆菌的rpoB基因的突变位置与耐药程度的关系。方法 32株对5 0 μg·mL-1的利福平耐药 (R5 0 )、2 2株对 2 5 0 μg·mL-1的利福平耐药 (R2 5 0 )、10株对利福平、异烟肼、乙胺丁醇及链霉素敏感的结核分枝杆菌株 (R0 )和 1株H3 7Rv结核分枝杆菌株包括核心区域在内的rpoB基因片段进行了DNA序列分析。结果 (1) 10株 (R0 )对利福平、异烟肼、乙胺丁醇及链霉素敏感的结核分枝杆菌株和 1株H3 7Rv结核分枝杆菌株未检测到rpoB基因易突变区的改变 ;(2 )耐利福平的低耐药 (R5 0 )结核分枝杆菌突变 2 5株 (78 1% ) ;耐利福平的高耐药 (R2 5 0 )结核分枝杆菌突变 2 1株 (95 5 % ) ,两者差异无显著性 (P =0 170 ) ;(3)耐利福平的低耐药 (R5 0 )结核分枝杆菌突变点呈散在分布 ;(4 )耐利福平的高耐药 (R2 5 0 )结核分枝杆菌突变以 5 31位氨基酸突变为主 (5 7 1% )以及联合突变较多见 (2 3 8% ) ,与R5 0相比两者差异有显著性。结论 大部分对利福平耐药的结核分枝杆菌均有rpoB基因突变。在对利福平低耐药结核分枝杆菌的rpoB基因中 ,其突变位置呈散在分布。在对利福平高耐药结核分枝杆菌的rpoB基因中 ,5 31位密码子突变及多个密码子联合突变是其主要突变特征。

Objective To study the mutation of DNA fragment of rpoB gene in different degrees of rifampin-resistance in Mycobacterium tuberculosis.Methods DNA fragment of rpoB gene in Mycobacterium tuberculosis was sequenced,including 32 low-level (R50) rifampin-resistant strains (50μg/mL rifampin-resistant),22 high-level (R250) rifampin-resistant strains (250μg/mL rifampin-resistant),10 (R0)rifampin-sensative strains and 1 H 37 Rv strain.Results No mutation was detected in 10 rifampin-sensative strains and 1 H 37 Rv strain;25(78.1%)rifampin-resistant strains had mutations in R50 and 21(95.5%)rifampin-resistant strains had mutations in R250(P=0.170).The mutatione points were distributed disorderly in R50.The 531-Ser mutation(57.1%)and joint mutation(23.8%)were more in R250 than those in R50.Conclusion The frequency of mutation in the rpoB gene of rifampin-resistant strain is higher.The mutation points are distributed disorderly in R50.The 531-Ser mutation(57.1%)and joint mutation(23.8%)are major mutative characteristics in R250.