Application of variable number tandem repeats in genotyping of Mycobacterium tuberculosis strains in Ningbo

Objective To conduct genotyping of Mycobacterium tuberculosis strains isolated from the patients in Ningbo with a new method based on the variable number tandem repeats (VNTR). Methods Seven VNTR loci were selected and the polymorphism of DNA fingerprinting of M. tuberculosis was analyzed with polymerase chain reaction (PCR) and agarose gel electrophoresis. Results The 7 VNTR loci of 138 M. tuberculosis strains were detected, and 7 clusters and 123 distinct patterns were found. The HGI value of VNTR-7 was 0.9991, and the percentage of VNTR-7 was 5.8%. The VNTR-3820 loci had the polymorphism. Conclusion The polymorphism of the M. tuberculosis isolates was obvious in Ningbo. The method of VNTR-7 showed high discrimination power in the detection of M. tuberculosis, which is easy to use and suitable for the TB control program.