Analysis On Genotyping Of Mycobacterium Tuberculosis Clinical Isolates By MLVA In DaLi District

ObjectiveA new method based on the Multiple locus variable number tandem repeatanalysis（MLVA）was applied for the genotyping of Mycobacterium tuberculosis inDali, To investigate the genotyping and distribution pattern of Mycobacteriumtuberculosis clinical isolates with MLVA.MethodsAt the beginning of the research, M. tuberculosis isolates of patient’s sputumsamples were collected in Laboratory Centers for Disease Surveillance of Dali BaiAutonomous Prefecture, following a study on its genotypes using MLVA. In theresearch,21loci were selected used to analyze the DNA. The polymorphism ofVNTR locus was tested in the DNA sample with PCR respectively. The clustering ofgenotype was analyzed with Quantity one and BioNumerics(6.6) software. The54dominant strains and Beijing family genotype obtained by comparing database wereall statistically analyzed by SPSS(13.0).Results1The detection of21VNTR loci showed that there was significant geneticpolymorphism existing in the120Mycobacterium tuberculosis of clinical isolatesand one standard strain of H37Rv. Hunter-Gaston index of21VNTR loci wentfrom0.301to0.838, in which the ten VNTR loci of MIRU26, Mtub21, Mtub30,Mtub39, Mtub4, MIRU31, MIRU16, Mtub29, MIRU10and MIRU40ownedhigher resolution, the ones of MIRU27, MIRU39, MIRU2, ETR-B, ETR-A MIRU26, MIRU23, MIRU4and Mtub34owned middle resolution, MIRU24andETR-C was the lowest VNTR loci.2By UPGMA method,121strains (including120clinical isolates and one standardstrain H37Rv) were divided into6genotype groups(I, II, III, IV,Ⅴ, Ⅵ). Amongthem, Group I made up50.4%（61/121）, Group II made up30.6%（37/121）,Group III made up6.6%（8/121）, Group IV made up5%（6/121）,Group Ⅴmadeup4.1%（5/121）, Group II made up3.3%（4/121）. Group I was mainly prevalentbacterial type, the standard strain was in the Group II.3By MST method,121strains (including120clinical isolates and one standardstrain H37Rv) were divided into6genotype groups(a, b, c, d, e, f). Among them,Group a accounted for86.7%(104/121) was the mainly prevalent genotype. Andthe standard strain was in the Group a.4The results showed that the Beijing family genotypes occupied73%(88/121), andthat non-Beijing family genotypes occupied23%(33/121), after comparing the120clinical isolates and one standard strain with database.5The chi-square test showed that there was no statistically significant differencebetween dominant genotypes and non-dominant genotypes in age(χ2=0.181，P=0.671)and gender (χ2=0.312，P=0.577).6The chi-square test showed that there was no statistically significant differencebetween Combined disease and non-Combined disease in age(χ2=2.788，P=0.095)and gender (χ2=2.094，P=0.148).Conclusion1MIRU26, Mtub21, Mtub30, Mtub39, Mtub4, MIRU31, MIRU16, Mtub29,MIRU10and MIRU40are the preferred locus for analyzing the120patients’Mycobacterium tuberculosis genotyping in Dali region. These ten loucs hadhigher Hunter-Gaston index.2The120strains of Mycobacterium tuberculosis in clinical isolates showedobvious genetic polymorphism. MLVA genotyping divided into at least sixgenotype groups. The predominant genotype groups were GroupⅠand Group a.Different counties and cities, its main genotype differences, most of the counties and cities are in conformity with the popular trend of overall.3Whether120patients infected clustering genotyping,dominant genotypes, doublestrain genotypes had nothing to do with gender, age of patients.4Loucs with different combinations had different Hunter-Gaston index in Dali byMLVA, the more the locs, the greater the HGI value.