First Insight into the Molecular Epidemiology ofMycobacterium tuberculosisIsolates from the Minority Enclaves of Southwestern China

Abstract

Yunnan is a province located in southwestern China. The aim of this study was to investigate the genetic diversity of Mycobacterium tuberculosis (MTB) strains circulating in Yunnan Province. We used spoligotyping and a 12-locus high-resolution VNTR set to identify a total of 271 MTB isolates collected from six prefectures' Yunnan. All the 271 patients were classified as 11 different ethnic groups, including 133 Han patients (49.1%) and 138 minority patients (50.9%). Spoligotyping analyses revealed that the largest two spoligotypes were SIT1 (Beijing family, n = 136) and SIT53 (T family, n = 35). Statistical analysis indicated that the proportion of Beijing genotype in Qujing was significantly higher than that in the ethnic enclaves (P ≤ 0.01). Compared with the percentage of Beijing-family isolates from patients under 25 years of age (72.7%), those from patients aged 45~64 years (44.6%, P < 0.01) and older than 64 years (48.1%) (P = 0.04) were significantly lower. Beijing genotype strains (23.8%, 36/151) showed higher clustering rate than non-Beijing genotype strains (16/120, 13.3%, P = 0.029). In conclusion, our data demonstrated that the Beijing genotype was the predominant genotype in Yunnan Province. The distribution of Beijing genotype strains showed geographic diversity. In addition, Beijing genotype was associated with recent transmission rather than drug resistance.

Genetic diversity and drug resistance of Mycobacterium tuberculosis in Yunnan, China

“…A highly different allelic diversity was identified in 430 MTB strains, and about 86.05% (370/430) of which showed unique genotype by using the 24‐locus MIRU‐VNTR. Moreover, the MTB strains had a relatively higher diversity in this study than that in Jiangsu strains (78.50%, 204/260), Tibet strains (44.29%, 229/517), and the strains reported (65.31%, 177/271) in Yunnan Province . Therefore, the 24‐locus MIRU‐VNTR analysis should be preferred in research and in clinical applications over the 12‐ or 15‐locus method.…”

“…Similar to the results of Chen et al, the Beijing family is the dominant lineage in Yunnan clinical MTB strains. However, the proportion of Beijing family is 55.7% and 70.47% in Chen et al and in this study ( P < 0.01), respectively.…”

“…MTB infection is one of the most serious infectious diseases in Yunnan, and the occurrence of drug‐resistant TB reached 37.91% in Yunnan MTB strains as reported by the Center for Disease Control and Prevention (CDC). Investigation on the genetic diversity of clinical MTB is a key way to control the prevalence of MTB in Yunnan Province, but several studies are performed in Yunnan MTB strains …”

“…Recently, the mycobacterial interspersed repetitive unit‐variable number tandem repeat (MIRU‐VNTR) method is the prevailing clinical technique because of its rapid, better repeatability, high‐throughput, and digitized analysis . Among the different sets of MIRU‐VNTR loci described for genotyping MTB isolates, a system based on 12, 15, and 24 loci is currently the most widely used in TB control systems in China . It aids in the elucidation of the phylogenetic relationships among clinical isolates and the identification of high‐risk groups that are susceptible to TB infection.…”

“…8,9 Among the different sets of MIRU-VNTR loci described for genotyping MTB isolates, 10,11 a system based on 12, 15, and 24 loci is currently the most widely used in TB control systems in China. 9,12,13 It aids in the elucidation of the phylogenetic relationships among clinical isolates and the identification of high-risk groups that are susceptible to TB infection. Beijing genotype is associated with drug resistance, showing an increased drug resistance level.…”