Evolution and transmission patterns of extensively drug-resistant tuberculosis in China.
The emergence and transmission of extensively drug-resistant tuberculosis (XDR-TB) pose an increasing threat to global TB control. This study aimed to identify the patterns of evolution and transmission dynamics of XDR-TB in populations in a region of China where TB is highly endemic. We analyzed a total of 95 XDR-TB isolates collected from 2003 to 2009 in Chongqing, China. Eight drug resistance genes covering 7 drugs that define XDR-TB were amplified by PCR followed by DNA sequencing. Variable-number tandem repeat 16-locus (VNTR-16) genotyping and genotypic drug resistance profiles were used to determine the evolution or transmission patterns of XDR-TB strains. Our results indicated that the Beijing genotype was predominant (85/95 [89.5%]) in XDR-TB strains, and as many as 40.0% (38/95) of the isolates were distributed into 6 clusters based on VNTR-16 genotyping and drug resistance mutation profiles. All isolates of each cluster harbored as many as six identical resistance mutations in the drug resistance genes rpoB, katG, inhA promoter, embB, rpsL, and gidB. Among the nine cases with continuous isolates from multidrug-resistant (MDR) to XDR-TB, 4 cases represented acquired drug resistance, 4 cases were caused by transmission, and 1 case was due to exogenous superinfection. The XDR-TB epidemic in China is mainly caused by a high degree of clonal transmission, but evolution from MDR to XDR and even superinfection with a new XDR strain can also occur.
Key Laboratory of Medical Molecular Virology, Huashan Hospital, Fudan University, Shanghai, China Department of Medical Microbiology and Parasitology, Shanghai Medical College, Fudan University, Shanghai, China.
Feifei
F
Wang
Key Laboratory of Medical Molecular Virology, Huashan Hospital, Fudan University, Shanghai, China.
Lingyun
L
Shao
Key Laboratory of Medical Molecular Virology, Huashan Hospital, Fudan University, Shanghai, China.
Xiaoping
X
Fan
Key Laboratory of Medical Molecular Virology, Huashan Hospital, Fudan University, Shanghai, China.
Yaojie
Y
Shen
Key Laboratory of Medical Molecular Virology, Huashan Hospital, Fudan University, Shanghai, China.
Ni
N
Diao
Key Laboratory of Medical Molecular Virology, Huashan Hospital, Fudan University, Shanghai, China.
Jialin
J
Jin
Key Laboratory of Medical Molecular Virology, Huashan Hospital, Fudan University, Shanghai, China.
Feng
F
Sun
Key Laboratory of Medical Molecular Virology, Huashan Hospital, Fudan University, Shanghai, China.
Jing
J
Wu
Key Laboratory of Medical Molecular Virology, Huashan Hospital, Fudan University, Shanghai, China.
Jiazhen
J
Chen
Key Laboratory of Medical Molecular Virology, Huashan Hospital, Fudan University, Shanghai, China.
Xinhua
X
Weng
Department of Medical Microbiology and Parasitology, Shanghai Medical College, Fudan University, Shanghai, China.
Xunjia
X
Cheng
Key Laboratory of Medical Molecular Virology, Huashan Hospital, Fudan University, Shanghai, China Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, USA.
Ying
Y
Zhang
Key Laboratory of Medical Molecular Virology, Huashan Hospital, Fudan University, Shanghai, China Institute of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China zhangwenhong@fudan.edu.cn.
Wenhong
W
Zhang
D000995:Antitubercular Agents / Q000627:therapeutic use; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D005075:Biological Evolution; D002681:China / Q000453:epidemiology; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D054908:Extensively Drug-Resistant Tuberculosis / Q000188:drug therapy / Q000635:transmission*; D005838:Genotype; D006801:Humans; D016133:Polymerase Chain Reaction; D018088:Tuberculosis, Multidrug-Resistant / Q000188:drug therapy / Q000635:transmission*
D000995:Antitubercular Agents; D001426:Bacterial Proteins