Comparison of virulence gene profiles and genomic fingerprints of Vibrio cholerae O1 and non-O1/non-O139 isolates from diarrheal patients in southern Thailand

Abstract

BackgroundVibrio cholerae is associated with severe watery diarrheal disease among people in many parts of the world, including the coastal provinces of Southern Thailand. There are relatively few studies focusing on the genetic characterization among V. cholerae isolates in this region. Therefore, this study aimed at exploring the presence of virulence genes and DNA fingerprints among V. cholerae O1 and non-O1/non-O139 isolates obtained from clinical samples in four southern coastal provinces during the period of 2001–2009 (n = 21).ResultsAll V. cholerae O1 isolates possessed ctxA, tcpA, zot, ace, hlyA, and vasH genes. However, only hlyA, vcsV2, and vasH genes were detected in the majority of the non-O1/non-O139 isolates. All O1 isolates showed indistinguishable PCR fingerprints by arbitrarily primed (AP)-PCR and enterobacterial repetitive intergenic consensus (ERIC)-PCR regardless of the geographical area and period of isolation. However, the multi-locus variable-number of tandem-repeat analysis (MLVA) could differentiate these O1 isolates (n = 11) into eight profiles. Isolates exhibiting an undistinguished MLVA profile also showed identical pulsed-field gel electrophoresis (PFGE). In addition, the O1 isolates were grouped into the same cluster by all methods used in this study.ConclusionsThis study demonstrated the presence of virulence genes and genetic diversity among different serogroups of V. cholerae isolates from clinical samples in southern Thailand. V. cholerae O1 isolated over a period of multiple years were genetically related, suggesting that they had a clonal origin, whereas non-O1/non-O139 isolates could have evolved independently.

Virulence, Resistance, and Genomic Fingerprint Traits ofVibrio choleraeIsolated from 12 Species of Aquatic Products in Shanghai, China

“… 60 The ERIC-PCR has been applied in clonal diversity and genotyping of V. cholerae isolates from clinical and environmental origins. 6 , 18 , 61 , 62 For instance, Xu et al reported 328 ERIC-genotypes among 400 V. cholerae isolates derived from 4 species of fish. 18 In this study, the 370 V. cholerae isolates recovered from the 12 species of aquatic products were classified into 239 ERIC-genotypes, 69.9% of which were assigned as singletons.…”

“…The major virulence genes ( ctxAB and tcpA ) (Kumar et al ) 33 and virulence-associated genes ( ace , zot , rtxABCD , hapA , hlyA , tlh , mshA , and pilA ). 6 , 11 , 18 , 34 were detected by PCR assay using the primer pairs listed in Table 1 . The PCR reaction conditions varied depending on the melting temperature (Tm) values of the primer pairs.…”

“… 18 A dendrogram was constructed by using BioNumeric software v.7.6. 6 Simpson's index of diversity was calculated as previously described. 36…”

“…Epidemic V. cholerae strains (serotypes O1 and O139) produce cholera toxin (CT) and toxin coregulated pilus (TCP). 6 Non-O1/O139 V. cholerae isolates carrying virulence-associated genes are widely distributed in aquatic ecosystems, and they can cause mild gastroenteritis, cholera-like diarrhea, sepsis, or other extraintestinal infections. [7][8][9][10][11][12] For instance, it has been reported that *77% of infection cases were caused by nontoxigenic V. cholerae in Northern Europe.…”

First Experimental Evidence for the Presence of Potentially Toxic Vibrio cholerae in Snails, and Virulence, Cross-Resistance and Genetic Diversity of the Bacterium in 36 Species of Aquatic Food Animals

“…The virulence and virulence-associated genes ctxAB , tcpA , ace , zot , rtxCABD , hapA , hlyA , tlh , mshA , and pilA were detected by PCR assay using the oligonucleotide primers [ 6 , 48 , 49 , 50 , 51 , 52 ] listed in Table S4 . PCRs were performed as described previously [ 6 ].…”