Abstract
BackgroundInvestigations of Mycobacterium tuberculosis genetic diversity in China have indicated a significant regional distribution. The aim of this study was to characterize the genotypes of clinical M. tuberculosis isolates obtained from Gansu, which has a special geographic location in China.Methodology/Principal FindingsA total of 467 clinical M. tuberculosis strains isolated in Gansu Province were genotyped by 15-locus mycobacterial interspersed repetitive units–variable number tandem repeats (MIRU-VNTR) and spoligotyping. The results showed that 445 isolates belonged to six known spoligotype lineages, whereas 22 isolates were unknown. The Beijing genotype was the most prevalent (87.58%, n = 409), while the shared type 1 was the dominant genotype (80.94%, n = 378). The second most common lineage was the T lineage, with 25 isolates (5.35%), followed by the H lineage with 5 isolates (1.07%), the MANU family (0.64%, 3 isolates), the U family (0.43%, 2 isolates) and the CAS lineage with 1 isolate (0.21%). By using the VNTR15China method, we observed 15 groups and 228 genotypes among the 467 isolates. We found no association between the five larger groups (including the Beijing genotype) and sex, age, or treatment status, and there was no noticeable difference in the group analysis in different areas. In the present study, seven of the 15 MIRU-VNTR loci were highly or moderately discriminative according to their Hunter-Gaston discriminatory index.Conclusions/SignificanceThe Beijing genotype is the predominant genotype in Gansu province. We confirm that VNTR15China is suitable for typing Beijing strains in China and that it has a better discriminatory power than spoligotyping. Therefore, the use of both methods is the most suitable for genotyping analysis of M. tuberculosis.
Highlights
Tuberculosis (TB) is a serious public health problem
Many polymerase chain reaction (PCR)-based methods were developed to avoid the technical demand of IS6110-RFLP, such as multiple locus variable number tandem repeat (VNTR) analysis (MLVA) and spacer oligonucleotide typing [5,6]
We previously described the VNTR15China typing scheme, and used it to analyse the genetic diversity of a large collection of isolates from more than 13 provinces in China [19,33]
Summary
Tuberculosis (TB) is a serious public health problem. Its causative agent, Mycobacterium tuberculosis (M. tuberculosis), may have killed more persons than any other microbial pathogen [1]. IS6110 restriction fragment length polymorphism (IS6110-RFLP) typing of M. tuberculosis has been the most widely applied and standardized molecular typing methods. This method is labor intensive and requires culturing large quantities of slow-growing M. tuberculosis. When strains harbor no copies, a single copy, or a few copies of IS6110 in their chromosomes, the discriminating efficiency of this method is lowered dramatically In this regard, many polymerase chain reaction (PCR)-based methods were developed to avoid the technical demand of IS6110-RFLP, such as multiple locus variable number tandem repeat (VNTR) analysis (MLVA) and spacer oligonucleotide typing (spoligotyping) [5,6]. The aim of this study was to characterize the genotypes of clinical M. tuberculosis isolates obtained from Gansu, which has a special geographic location in China
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