title: Genotypic diversity of multidrug-, quinolone- and extensively drug-resistant Mycobacterium tuberculosis isolates in Thailand.
abstract: Drug-resistant tuberculosis (TB), which includes multidrug-resistant (MDR-TB), quinolone-resistant (QR-TB) and extensively drug-resistant tuberculosis (XDR-TB), is a serious threat to TB control. We aimed to characterize the genotypic diversity of drug-resistant TB clinical isolates collected in Thailand to establish whether the emergence of drug-resistant TB is attributable to transmitted resistance or acquired resistance. We constructed the first molecular phylogeny of MDR-TB (n=95), QR-TB (n=69) and XDR-TB (n=28) in Thailand based on spoligotyping and proposed 24-locus multilocus variable-number of tandem repeat analysis (MLVA). Clustering analysis was performed using the unweighted pair group method with arithmetic mean. Spoligotyping identified the Beijing strain (SIT1) as the most predominant genotype (n=139; 72.4%). The discriminatory power of 0.9235 Hunter-Gaston Discriminatory Index (HGDI) with the 15-locus variable-number tandem repeats of mycobacterial interspersed repetitive units typing was improved to a 0.9574 HGDI with proposed 24-locus MLVA, thereby resulting in the subdivision of a large cluster of Beijing strains (SIT1) into 17 subclusters. We identified the spread of drug-resistant TB clones caused by three different MLVA types in the Beijing strain (SIT1) and a specific clone of XDR-TB caused by a rare genotype, the Manu-ancestor strain (SIT523). Overall, 49.5% of all isolates were clustered. These findings suggest that a remarkable transmission of drug-resistant TB occurred in Thailand. The remaining 50% of drug-resistant TB isolates were unique genotypes, which may have arisen from the individual acquisition of drug resistance. Our results suggest that transmitted and acquired resistance have played an equal role in the emergence of drug-resistant TB. Further characterization of whole genome sequences of clonal strains could help to elucidate the mycobacterial genetic factors relevant for drug resistance, transmissibility and virulence.
authors.affiliation: Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
authors.forename: Areeya
authors.initials: A
authors.lastname: Disratthakit
authors.affiliation: Department of Mycobacterium Reference and Research, Research Institute of Tuberculosis, Japan Anti-tuberculosis Association, Tokyo 204-8533, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Meada
authors.affiliation: National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Ministry of Science and Technology, Pathum Thani 12120, Thailand.
authors.forename: Therdsak
authors.initials: T
authors.lastname: Prammananan
authors.affiliation: Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
authors.forename: Iyarit
authors.initials: I
authors.lastname: Thaipisuttikul
authors.affiliation: Department of Pathophysiology and Host Defense, Research Institute of Tuberculosis, Japan Anti-tuberculosis Association, Tokyo 204-8533, Japan.
authors.forename: Norio
authors.initials: N
authors.lastname: Doi
authors.affiliation: Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand. Electronic address: angkana.cha@mahidol.ac.th.
authors.forename: Angkana
authors.initials: A
authors.lastname: Chaiprasert
mesh_terms: D000995:Antitubercular Agents / Q000494:pharmacology; D003001:Cloning, Molecular; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D054908:Extensively Drug-Resistant Tuberculosis / Q000382:microbiology*; D056426:Genetic Loci; D014644:Genetic Variation; D005838:Genotype; D060005:Genotyping Techniques; D006801:Humans; D018598:Minisatellite Repeats; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification*; D010802:Phylogeny; D015363:Quinolones / Q000494:pharmacology; D013785:Thailand / Q000453:epidemiology
chemical_list: D000995:Antitubercular Agents; D004269:DNA, Bacterial; D015363:Quinolones
keywords: Extensively drug-resistant; Genotypic diversity; MLVA; Multidrug resistance; Thailand; Tuberculosis