Genetic diversity and drug susceptibility patterns of the Mycobacterium tuberculosis complex in Yunnan, China.

Ruolan Bai,Yunfeng Bi,Xiaofei Li,Lisha Luo,Zhenhua Ji,Miaomiao Jian,Feng Wang,Aihua Liu,Xiting Dai,Shuijing Chi,Taigui Chen,Zhe Ding,Fukai Bao

doi:10.1042/bsr20181746

Abstract

Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (Mtb) which has been threatening global public health for many years. High genetic diversity is dominant feature of Mtb. Increasing cases of multidrug-resistant (MDR) tuberculosis (MDR-TB) is a serious public health problem to TB control in China. Spontaneous mutations in the Mtb genome can alter proteins which are the target of drugs, making the bacteria drug resistant. The purpose of the present study was to analyze the genotype of Mtb isolates from some areas in Yunnan, China and explore the association between genotypes and MDR-TB. Using spoligotyping, we identified Beijing genotypes, six non-Beijing genotypes and a number of orphan genotypes from 270 Mtb isolates from patients in Yunnan Province during 2014–2016. Of 270 Mtb isolates, 102 clinical Mtb strains were identified as drug-resistant (DR) by drug susceptibility testing (DST), among them, 52 MDR strains. Beijing genotypes occupied the highest MDR proportion (78.85%) followed by the orphan genotypes (15.38%). The characteristics of MDR strains showed high genetic diversity. The results will help to efficiently improve diagnosis and treatment and provide valuable information for Mtb molecular epidemiology.

Highlights

Under persistent threat of drug-resistant (DR) tuberculosis (DR-TB), 480000 cases of multidrug-resistant (MDR) tuberculosis (MDR-TB) emerged in 2015, and the countries with the largest numbers of MDR-tuberculosis (TB) cases were China, India, and the Russian federation (47% of the global total) with nearly a quarter of MDR-TB worldwide burden in China [1]
Out of these isolates, 52 (19.3%) isolates were classified as MDR [1] (MDR-TB is TB that is resistant to both rifampicin and INH, the two most powerful anti-TB drugs), and the proportion of Beijing genotype isolates was 78.8% (41/52) out Lineage Non-Beijing H3 U MANU2 T
A study from Chen et al [14] probed the molecular epidemiological characteristics of Mycobacterium tuberculosis (Mtb) strains collected in Yunnan Province in 2014, and found that Beijing genotype is the main genotype of Yunnan Province, which is similar to our results

Summary

Introduction

Under persistent threat of drug-resistant (DR) tuberculosis (DR-TB), 480000 cases of multidrug-resistant (MDR) tuberculosis (MDR-TB) emerged in 2015, and the countries with the largest numbers of MDR-tuberculosis (TB) cases were China, India, and the Russian federation (47% of the global total) with nearly a quarter of MDR-TB worldwide burden in China [1]. Findings from a recent national survey in China demonstrated that the prevalence of smear-positive tuberculosis is 19% [2]. According to a recent survey in China, it was demonstrated that the percentage of MDR-TB cases is 16.7%, and extensively DR-TB cases is 3.4% [3]. Some studies have suggested that relatively serious TB prevalence may occur in Western and Southwestern China [4]. Yunnan Province, as one of the areas with the most serious TB prevalence, is located on the Southwestern Chinese border [5]. Yunnan stands at China’s border with Southeast Asia and South Asia (the point at which India is located) and is a famous tourist resort that attracts many tourists from all over the world. Extensive MDR-MTB transmission would be more likely to occur among tourists if epidemic genotypes with MDR transmission dynamic observed in the study spread uncontrollably

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