结核分支杆菌异烟肼耐药的分子机制及其快速鉴定

目的：探讨快速检测结核分支杆菌异烟肼耐药的分子药敏方法。方法：用聚合酶链反应-单链构象多态性(PCR-SSCP)检测了20株异烟肼(INH)敏感的结核杆菌临床分离株，20株INH耐药株的katG基因，随后用SSCP方法鉴定扩增产物有无突变，以结核分支杆菌H37RV作对照。结果：所有INH敏感株均观察到katG基因扩增产物，20株INH耐药株中19株观察到katG基因扩增产物。以H37RV标准株为对照，20株敏感株SSCP带谱与对照相同；19株INH耐药株中8株与对照相同，11株有不同程度的差异，INH耐药katG基因突变或缺失的阳性率为60％。结论：多数结核分支杆菌耐INH是由于其katG基因突变所致，用PCR-SSCP筛选突变株可达到快速检测结核分支杆菌INH耐药的目的。

The Molecular Mechanism and Fast Detection of Isoniazid Resistance of Mycobacterium Tuberculosis

Objective To evaluate the feasibility of detecting katG gene mutation associated with isoniazid resistance by PCR SSCP technique. Methods 20 isoniazid susceptible Mycobacterium tuberculosis clinical isolates and 20 isoniazid resistant isolates were analyzed by PCR SSCP technique, with Mycobacterium tuberculosis H37RV reference strains as control group. The detection method involved the amplification of the isoniazid resistance region of katG gene by PCR and the identification of mutations of the amplification products by SSCP analysis. Results Amplification was observed in all clinical isolates except 1 isoniazid resisant isolates. 20 isoniazid susceptible clinical isolates and M. tuberculosis H37RV displayed identical SSCP patterns. Among 19 isoniazid resistant chinical isolates, 11 isolates showed PCR SSCP patterns different from that of H37RV, and 8 isolates displayed the same patterns as H37RV. About 60 percent isoniazid resistant clinical isolates showed mutation or deletion of katG gene by SSCP analysis. Conclusion The changes of katG gene are associated with isoniazid resistance. PCR SSCP technique will be useful to rapidly screen gene mutation of isoniazid resistant M. tuberculosis.