| description |
Cholera is still an important public health problem in several countries including Thailand. In this study, a collection of clinical and environmental V. cholerae serogroup O1, O139, and non-O1/non-O139 strains collected between 1983 and 2013 in Thailand were characterized to determine phenotypic and genotypic traits and investigation of the genetic relatedness. Seventy-eight V. cholerae strains were identified using a combination of standard conventional methods and whole genome sequencing (WGS). WGS was used to determine the serogroup, biotype, virulence, mobile genetic elements, and antimicrobial resistance genes using online bioinformatics tools. In addition, phenotypic antimicrobial resistance was determined by the minimal inhibitory concentration (MIC) test. The Seventy-eight V. cholerae strains belonged to the following serogroups O1: (n=44), O139 (n=16) and non-O1/non-O139 (n=18). Interestingly, we found that the typical El Tor O1 strains were the major cause of clinical cholera during 1983-2000 with two classical O1 strains detected in 2000. The El Tor variant strains revealed genotypes of the classical biotype possessing either only ctxB or both ctxB and rstR while they harbored tcpA of the El Tor biotype. Thirty-four O1 and fifteen O139 clinical strains carried CTXφ and tcpA as well four different PALs. Beside non-O1/non-O139, the O1 environmental strains also presented chxA and TTSS. The in silico MLST discriminated the O1 and O139 clinical strains from other serogroups and environmental strains. ST69 was dominant in the clinical strains belonging to the 7th pandemic clone. Non-O1/non-O139 and environmental strains showed various novel STs indicating genetic variation. Multidrug-resistant (MDR) strains were observed and conferred resistance to ampicillin, azithromycin, nalidixic acid, sulfamethoxazole, tetracyclin, and trimethoprim and harboured a variant of the SXT element. For the first time since 1986, the presence of V. cholerae O1 classical was reported causing cholera outbreaks in Thailand. In addition, we found that V. cholerae O1 variant El Tor and O139 were pre-dominating the pathogenic strains in Thailand. Using WGS and bioinformatic tools to analyze both historical and contemporary V. cholerae circulating in Thailand, provided a more detailed understanding of the V. cholerae epidemiology, and ultimately could be applied for control measures and management of cholera in Thailand. |