基因芯片技术检测贵州省结核分枝杆菌耐药基因KatG和inhA

目的 了解本地区结核分枝杆菌(MTB)异烟肼(INH)相关耐药基因katG和inhA的突变特征,评价基因芯片法对MTB INH耐药性检测的临床应用价值。方法 应用基因芯片法对经PCR-荧光探针法鉴定为MTB阳性的2 738例病人标本进行INH耐药性检测,分析其相关耐药基因katG和inhA的突变特征,同时应用比例法检测上述同期送检的相同病人的同类型标本经罗氏培养MTB阳性菌株的INH耐药性,比较两种方法的检测结果。结果 2 738例MTB核酸阳性标本经基因芯片法检测,INH耐药465例,耐药率16.98%,其中以katG 315(AGC→ACC)突变为主,基因突变率为78.06%,其次为inhA -15(C→T),katG 315(AGC→AAC),突变率分别为16.13%和5.59%。上述病人同期送检的同类型标本有1 493例经罗氏培养MTB阳性,比例法检测,INH耐药255例,耐药率17.08%,对应的基因芯片法检测结果为INH耐药249例,耐药率16.68%。以比例法结果为判断标准,基因芯片法测定INH耐药性的敏感性、特异性、阳性预测值(PPV)、阴性预测值(NPV)及准确性分别为85.49%、97.50%、87.55%、97.03%和95.45%。结论 本地区INH耐药以katG 315(AGC→ACC)和inhA -15(C→T)突变类型为主;基因芯片对MTB INH耐药性检测具有高敏感性、特异性、准确性和快速性,可用于本地区MTB INH耐药性的快速检测。

Determination of resistance genes KatG and inhA in Mycobacterium tuberculosis isolates from Guizhou Province by gene chip

We aimed to investigate the characteristics of KatG and inhA gene mutations of Mycobacterium tuberculosis (MTB) associated with INH in Guizhou Province, and to evaluate the clinical application value of gene chip in MTB resistance detection. Resistance to INH of 2 738 clinical samples were detected by gene chip method. These samples were determined as MTB positive by PCR-fluorescent probe method. Characteristics of mutations of INH resistance gene KatG and inhA were then analysed. Meanwhile, MTB were isolated from these samples by Lowenstein-Jensen method and INH resistance were detected by ratio method. Susceptibility results determined by these two methods were compared. Of 465 samples in 2 738 MTB nucleic acid positive samples were resistant to INH determined by gene chip method, and the rate was 16.98%. Gene mutations were mainly found in katG 315(AGC→ACC)and the mutation frequency was 78.06%. The inhA -15 (C→T) mutation was in the second place and the katG 315 (AGC→AAC) was in the third place, and the mutation frequency was 16.13% and 5.59%, respectively. A total of 1 493 MTB strains were isolated from the same samples of the above patients. Being determined by conventional ratio method, 255 MTB strains were detected as resistant to INH, with the rate of 17.08%. INH resistance was judged according to the conventional method, and the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of the gene chip method was 85.49%, 97.50%, 87.55%, 97.03% and 95.45%, respectively. In conclusion, gene mutations related with MTB resistance to INH were mainly happened at the KatG 315 (AGC→ACC) and the inhA -15 (C→T) in Guizhou Province. Gene chip is a rapid test method with high sensitivity, specificity and accuracy, which could be used in the fast detection of the MTB drug resistance to INH.