Study On The Correlation Between MIRU Loci Like MTUB21 And Drug Resistant Tuberculosis

Objective: Few studies reported that whether the MIRU loci were correlated with Mycobacterium tuberculosis and what is the exact anti-tuberculosis drug that the MIRU loci related to.This study is aimed to evaluate the association between the MIRU loci such as MTUB21 and the anti-tuberculosis resistant drug such as Isoniazid(INH),rifampicin(RFP),streptomycin(SM),ethambutol(EMB)and pyrazinamide(PSA).Methods: The collected strains were evaluated by sputum smear test and the posicitive ones were selected to be inoculated in acidic L-J medium,p-nitrobenzoic acid indicator culture-medium and thiophene-2-carboxylic acid hydrazide.The drug susceptibility test was performed for strains positive in all 3 mediums mentioned above,including INH,RFP,SM.EMB,PSA.The DNA of samples were extracted as models and the sequences of 15 MIRU loci such as MTUB21 were amplified by PCR.After amplify,the PCR products were analyzed by gel electrophoresis.The number of MIRU loci were calculated by specific table tools according to the gel electrophoresis band.The statistical analysis was performed by version 16.0 of SPSS software.The frequency distribution of drug resistance of 105 strains and the number of copies of each corresponding MIRU loci was evaluated by descriptive statistical analysis.Single and multiple logistic regression analysis were conducted to evaluate the association between MIRU loci and drug resistance.In addition,the genetic differences and resolution ratio of MIRU sites was analyzed by Microsoft Excel 2007.P<0.05 was considered to be statistically significant difference.Results: The order of resolution ratio of 15 MIRU loci was as follows:MTUB21>MTUB04>MIRU26>QUB11b>MIRU16>MIRU39>MIRU20>MIRU27>ET RE>MIRU10>MIRU40>ETRA>ETRD>ETRB>ETRC.Multi-variable logistic regression showed that,ETRB(P=0.022,OR=0.104,95%CI: 0.015-0.718)was the negative factor of INH resistance;MTUB21(P=0.018,OR=0.560,95%CI: 0.347-0.906)was negative factor of RFP resistance;MIRU20(P=0.049,OR=9.162,95%CI: 1.011-83.015)was stimulative factor for SM resistance while the MTUB21(P=0.024,OR=0.425,95%CI: 0.203-0.891)was negative factor;MIRU 27(P=0.040,OR=0.299,95%CI: 0.095-0.945)was considered to be negative factor of EMB resistance;ETRA(P=0.024,OR=0.396,95%CI: 0.177-0.887)was shown to be negative factor of PSA resistance.Conclusion: There were differences between the resolution ratios of MIRU loci.Part of MIRU loci were related to drug resistance(ETRB and INH resistance;MIRU21,MTUB21 and RFP resistance;MIRU27 and EMB resistance;ETRA and PSA resistance).The mechanism may be that MIRU loci up or down regulate the expression near genes,affecting the expression of translation products such as mycolic acid,so as to lead to the drug resistance.