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Molecular and genomic investigations into spreading and diversification of Vibrio cholerae O1 in Thailand

Year: 2012
Type: article
Abstract: Background: Cholera epidemics break out occasionally in Thailand. This study aims to characterize V. cholerae O1 isolated in Thailand during 2007 to 2010. Methods: V. cholerae O1 isolates collected from cholera patients, their family members, and neighbors, as well as environmental samples in cholera outbreak sites. PCR was carried out for detection of theseveral markers, rtxC, rstR, ctxA, zot, ace, tcpA, ompU, toxR and ctxB genes. The presence or absence of ORFs in the Vibrio seventh pandemic island I (VSP-I) and II (VSP-II) clusters of selected isolates was examined. In addition, the isolates were characterized using pulsed-field gel electrophoresis (PFGE), ribotyping, multilocus variable-number tandem repeat analysis (MLVA). Results: We found almost all of the 343 isolates obtained carried the classical cholera toxin gene and El Tor rstR genes. PFGE differentiated the isolates into 10 distinct pulsotypes, clustered into two major groups. Ribotyping, MLVA, and PCR to detect VSP-II related genes of randomly selected isolates from each pulsotype corresponded to the results obtained by PFGE. MLVA typing among isolates revealed geographical and temporal associations of causative V. cholerae in cholera outbreaks. The 2007 cholera outbreaks in northeastern Thailand were triggered by the consumption of cockles contaminated with V. cholerae O1 MLVA type 2. On the other hand, outbreaks in the southern Gulf areas outbreaks in 2009 were linked mainly with MLVA types 7 and 12, while those in the central Gulf areas during 2009–2010 were linked with MLVA type 4. MLVA type 41 continued to exist predominantly in an outbreak site for more than three years. Long-term survival of V. cholerae O1 of a particular MVLA type, such as type 41, may be attained in watery environments or in humans. It should be noted here that one V. cholerae O1 carrying the El Tor type ctxB which did belong to neither groups. Conclusion: Our epidemiological results are highly rewarding in terms of reference to emergence, year-long survival, or disappearance of particular type(s) of isolates with special reference to spatial and temporal associations of the organisms.
DOI: 10.1016/j.ijid.2012.05.850
Language: English
Subfield: Microbiology
Open Access status: gold
Estimated APC paid: $2,900
OpenAlex ID: W2046579652
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