Study on genotyping of 344 strains of Mycobacterium tuberculosis

OBJECTIVE To investigate the genotyping and distribution pattern of the variable number tandem repeats(VNTR) of Mycobacterium tuberculosis clinical isolates in Henan province with Multi-locus VNTR analysis preliminarily.METHODS M.tuberculosis clinical isolates selected from Henan province randomly were cultured with Lowenstein-Jensen medium.The genome DNA of the bacteria was extracted.The polymorphism of VNTR locus was tested in the DNA samples with PCR respectively.The clustering of genotype was analyzed with BioNumerics(Version5.0).Chi-Square test was used for statistical analysis.RESULTS 86.9%of the strains belongs to Beijing genotype,Beijing genotype was not significantly associated with the resistance to all of the four first line drugs,but was significantly associated with the MDR.12 MIRUs loci of 344 M.tuberculosis clinical isolates were analyzed respectively.The results showed that there were obvious polymorphisms of VNTRs.The clustering of genotype showed that these strains could be categorized into gene clusters(Ⅰ,Ⅱ,Ⅲ,Ⅳ and Ⅴ)and 292 genotypes.5.1% were cluster Ⅰ including 15genotypes,67.8% were clusterⅡincluding 198 genotypes,21.9 % were cluster Ⅲ including 64 genotypes,1.4% were cluster Ⅳ including 4 genotypes,2.8% were cluster Ⅴ including 11 genotypes.CONCLUSION The result shows that there are obvious polymorphisms of MIRUs of M.tuberculosis clinical strains preliminarily.There are at least 5 clusters of MIRU genotype and cluster Ⅱ is the predominant prevalent strain in Henan province.There is no correlation exists between the drug resistant and beijing family Genotypes.