Multipleloci Variable-number Tandem Repeat Typing of Clinical Mycobacterium tuberculosis Isolates from Zunyi, Guizhou Province of China

Introduction: Due to the emergence of multidrug/extensively drug-resistant TB and the lack of new anti-TB drugs, tracing the infectious source and monitoring the transmission of drug-resistant TB strains have become critically important. Methods: To determine which VNTR locus set is more suitable for use in Zunyi, China, we used 19 VNTR loci including 4 recommended by the China CDC, 4 recommended a group of scientists from Europe and USA, and 11 recommended by both for molecular typing of 100 clinical M. tuberculosis isolates from Zunyi, Guizhou Province of China. PCR amplified DNA fragments were analyzed by comparing their sizes on the gel images with those amplified from the reference M. tuberculosis H37Rv strain at each of the 19 corresponding VNTR loci to determine copy numbers of each VNTR. The cluster analysis was carried out by using the Bionumerica 5.0 software.