Research On The Relationship Between Mutation Sites Of RpoB?katG And InhA Gene And Their Minimal Inhibitory Concentration Of Mycobacterium Tuberculosis

Objective:To investigate the effects of different mutation sites of rpoB,katG and inh A in Mycobacterium tuberculosis on the minimal inhibitory concentration(MIC)in vitro so as to provide reference for clinical medication.The drug resistance genes of RFP and INH were detected by gene chip technology and the results were compared with the conventional drug susceptibility in order to evaluate the chip detection technology.Methods:Collecting the mutant and wild strains of Mycobacterium tuberculosis randomly by gene chip technology in the Changsha Central Hospital between January 1,2014 and December 30,2015.All the strains were recovered by Roche method and performed drug sensitivity test in a serial of concentrations of RFP and INH,then observing the effects of different mutant strains of the resistance-gene about RFP and INH on the MIC and evaluating the chip detection technology as well.Results:1.In the RFP test,the MIC of 58 wild strains is 8.84±10.3?g/ml.Drug phenotype of the mutant strain 531(C to T)was the highest,which MIC was 576.0±131.3?g/ml,followed by 516(A to G/T),432.9±157.6?g/ml and 526(C to G/T),355.6±252.6.There were statistical significance of MIC between 531(C to T)and 526(C to G/T),531(C to T)and516(A to G/T)(p=0.016<0.05 and p=0.033<0.05).But it was not difference between 516(A to G/T)and 526(A to G)(p=0.849>0.05).The MIC of wild strains was significantly lower than the mutation group(p<0.05).The mutations of other unit site,double sites and three sites had higher MIC.2.Compare the proportion Method,68 strains in 69 resistant strains were mutations detected by gene chip method,The sensitivity was 98.6%,57 strains in 60 sensitive strains were wild,the specificity was 95.0%,there was no significant difference between the two methods(?~2=0.062,P=0.803>0.05).3.In the INH test,the MIC of 32 wild strains was 0.06±0.05?g/ml.The MIC of 20 strains with inhA-15(C to T)was 0.37±0.09?g/ml,46strains with katG315(G to C/A)was 5.76±4.06?g/ml.The MIC of the mutation inhA-15 was higher than the wild strains,but was lower than the mutation katG315.There was significant difference in each group(p<0.05).4.Compare the proportion Method,65 strains in 68 resistant strains were mutations detected by gene chip,the sensitivity was 95.6%,29strains in 30 sensitive strains was wild,the specificity was 96.7%,There was no significant difference between the two methods(?~2=0.094,P=0.759>0.05).Conclusion:1.The principal Mutation sites of RFP and INH in Mycobacterium tuberculosis were rpoB531,katG315 and inhA-15 in Changsha Central Hospital.2.The resistance of RFP and INH was caused by different mutations.Different mutation patterns cause different levels of drug resistance.3.The gene chip were highly consistent with the traditional drug sensitive method.The chip can replace the traditional method for rapid screening of rifampin resistance.