结核分枝杆菌对异烟肼和利福平的耐药水平与其耐药基因突变的相关性研究

目的 探讨Mtb耐药相关基因katG、inhA、oxyR-ahpC突变与对INH的耐药水平及rpoB突变与对RFP的耐药水平的关系。 方法 采用微孔板Alamar blue显色法分别检测59株耐INH的Mtb临床分离株对INH和30株耐RFP菌株对RFP的最低抑菌浓度（the minimum inhibitory concentration，MIC），同时用直接测序法检测对INH耐药菌株katG、inhA、oxyR-ahpC和对RFP耐药菌株rpoB的突变情况。 结果 INH MIC为0.2500~1.0000 μg/ml（低水平耐药菌株）和 MIC≥2.0000 μg/ml（高水平耐药菌株）的INH耐药株，inhA启动子突变率前者高于后者［53.8% (7/13)，4.3% (2/46)］，katG 315突变率前者低于后者［15.4% (2/13)，76.1% (35/46)］，χ²值分别为15.57和13.48，P值均为0.000。RFP MIC为0.5000～16.0000 μg/ml和MIC≥32 0000 μg/ml的RFP耐药株，rpoB 531和526位总突变率前者低于后者［62.5% (5/8)，95.5%(21/22)］，P_确切概率＝0.048。 结论 INH耐药菌株inhA启动子突变与INH低水平耐药有关，katG 315突变与INH高水平耐药有关；rpoB 531和526位突变与RFP高水平耐药有关。

Correlation between levels of isoniazid and rifampicin resistance and targeted gene mutations in Mycobacterium tuberculosis

Objective To determine the correlation between isoniazid resistance level and the mutations in katG,inhA promoter and oxyR-ahpC,and the correlation between rifampicin resistance level and the mutations in rpoB in Mycobacterium tuberculosis.Methods Microplate alamar blue assay was used to determine the isoniazid MIC in 59 isoniazid-resistant Mycobacterium tuberculosis clinical isolates and the rifampicin MIC in 30 rifampicin-resistant isolates,and direct sequencing was used to detect the mutations of katG,inhA promoter and oxyR-ahpC in isoniazid-resistant isolates and the mutations of rpoB in rifampicin-resistant isolates.Results Among isoniazid-resistant isolates with MIC from 0.2500 to 1.0000 μg/ml and MIC≥2.0000 μg/ml,7 out of 13 and 2 out of 46 isolates carried mutations in inhA promoter respectively,and 2 out of 13 and 35 out of 46 isolates carried mutation in codon katG 315 respectively,the χ2 values were 15.57 and 13.48,respectively,the P values were all 0.000.Among rifampicin-resistant isolates with MIC from 0.5000 to 16.0000 μg/ml and MIC≥32.0000 μg/ml,5 out of 8 and 21 out of 22 isolates carried mutations in codon rpoB 531 and 526,the exact P value was 0.048.Conclusion Mutations in inhA promoter and katG 315 were correlated with low level and high level of isoniazid resistance respectively.rpoB mutations in codon 531 and 526 were associated with high level of rifampicin resistance.