In vitro minimum inhibitory concentration of Mycobacterium tuberculosis isoniazid-resistant gene mutants

Objective To study katG,inhA and ahpC mutations of Mycobacterium tuberculosis isoniazid-resistant clinical isolates,and their effect on minimum inhibitory concentration(MIC) in vitro.Methods Isoniazid-resistant genes of 160 Mycobacterium tuberculosis isoniazid-resistant strains and 40 isoniazid-sensitive strains were detected by gene chip.All samples with different gene mutations were determined and compared MICs of iso-niazid.Results Of isoniazid-resistant strains,68.8%(110/160) had katG315 mutations,the MICs of katG315 gene mutants(20.20±19.46 μg/ml)was significantly higher than inhA gene mutants(0.73±0.82 μg/ml,t′=10.9171,t′ α=1.9807,P0.05),and significantly lower than katG315 plus inhA gene mutants(69.33±32.45 μg/ml,t′= 7.164,t′ α= 2.0627,P0.05).Conclusion Isoniazid-resistant strains had different gene mutation patterns,different genotypes had different levels of isoniazid resistance,which can provide a reference to the clinical.