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目的了解贵阳地区分离的结核分枝杆菌katG基因、inhA启动子和oxyR-aphc间隔区基因突变特征。方法对31株结核分枝杆菌临床分离株(异烟肼耐药株17株,异烟肼敏感株14株)的katG基因、inhA启动子和oxyRaphc间隔区进行DNA片段的PCR扩增,并进行测序分析。结果 17株异烟肼耐药菌株中有16株检出katG基因突变,其中70.5%(12/17)为315位密码子变异,且变异类型均为AGC→ACC,敏感株未发现315位点突变。11株敏感菌和4株耐药菌在463位密码子发生变异,变异类型均为CGG→TGG,变异率分别为78.6%(11/14)和23.5%(4/17),差异无统计学意义。有12株耐药株的变异类型为katG基因双重位点突变,其中10株为katG315(AGC→ACC)和463(CGG→TGG)位变异,463(CGG→TGG)和299(GGC→AGC)变异及463(CGG→TGG)和419(GAC→CAC)位变异各1株。2株异烟肼耐药菌检出oxyR-aphC启动区G32A突变,其中1株为联合katG463和299位突变。结论贵阳株结核杆菌菌株异烟肼耐药基因突变具有多态性,主要的变异类型为katG315位点突变。
Objective To understand the mutations of the katG gene, inhA promoter and oxyR-aphc spacer in Mycobacterium tuberculosis isolated in Guiyang. Methods DNA fragments were amplified by PCR from 31 strains of Mycobacterium tuberculosis clinical isolates (17 isoniazid-resistant strains and 14 isoniazid-sensitive strains) by katG gene, inhA promoter and oxyRaphc spacer. Sequencing analysis. Results 16 out of 17 isoniazid-resistant isolates were detected katG gene mutations, of which 70.5% (12/17) of 315 codon variations, and the types of variation were AGC → ACC, sensitive strains did not find 315 loci mutation. The mutations at codon 461 of 11 strains of susceptible and 4 strains of resistant bacteria were all CGG → TGG with the mutation rates of 78.6% (11/14) and 23.5% (4/17) respectively, with no statistical difference significance. Among the 12 strains, the mutation type of katG gene was double locus mutation of katG gene, of which ten were katG315 (AGC → ACC) and 463 (CGG → TGG), 463 (CGG → TGG) and 299 (GGC → AGC) Mutation and 463 (CGG → TGG) and 419 (GAC → CAC) bit mutation of a strain. Two isoniazid resistant isolates detected a G32A mutation in the oxyR-aphC promoter region, of which one was a combination of katG463 and a 299-residue mutation. Conclusion The mutation of isoniazid resistance gene in Mycobacterium tuberculosis strains in Guiyang is polymorphic. The main mutation type is katG315 mutation.