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为了了解我国结核分枝杆菌耐异烟肼 (INH)分离株katG基因突变情况 ,研究其临床意义。本研究通过聚合酶链反应 (PCR)、PCR 单链构象多态性 (SSCP)和PCR直接测序法 (directsequencing ,DS)分析 92株结核分枝杆菌临床分离株的katG基因。以H37Rv标准株为对照 ,2 3株药物敏感株中 ,2 1株katG基因SSCP分析正常 ,2株异常。 36株耐非INH药物的分离株中 ,2 0株katG基因SSCP正常 ,16株异常。 33株耐INH分离株中 ,高度耐INH的 17株 ,其中 4株为katG基因缺失 ,5株katGSSCP异常 ,8株正常 ;低度耐INH的 16株 ,其中 13株KatG基因SSCP异常 ,3株正常。上述所有katGSSCP异常的分离株DS分析均为 315位密码子突变 ,除 1株为AGC→AAC突变外 ,其余均为AGC→ACC突变。结果表明katG基因突变是结核分枝杆菌耐INH产生的主要分子机制 ,其最常见的 315位密码子突变可引起结核分枝杆菌轻度或中度耐INH。
In order to understand the mutation of katG gene of mycobacterium tuberculosis isolates of INH in China, the clinical significance of katG gene mutation was studied. In this study, katG gene of 92 clinical isolates of Mycobacterium tuberculosis was analyzed by polymerase chain reaction (PCR), PCR single strand conformation polymorphism (SSCP) and direct sequencing (PCR). H37Rv standard strains as a control, 23 strains of drug-sensitive strains, 21 katG gene SSCP normal, 2 were abnormal. Of the 36 non-INH drug-resistant isolates, 20 normal katG gene SSCP and 16 abnormal. Of the 33 INH isolates, 17 were highly resistant to INH, of which 4 were deletion of katG gene, 5 were abnormal in katGSSCP and 8 were normal; 16 were INH-resistant, of which 13 were SSCP anomalies and 3 normal. All of the above katGSSCP abnormal isolates were analyzed by the codon 315 codon mutation, except for one strain of AGC → AAC mutation, the others were AGC → ACC mutations. The results show that katG gene mutation is the major molecular mechanism of INH resistance in M. tuberculosis. The most common 315 codon mutation causes M. tuberculosis to be mild or moderately resistant to INH.