Detection of virulence-associated and regulatory protein genes in association with phage typing of human Vibrio cholerae from several geographical regions of the world

Vibrio cholerae O1, O139 and occasionally non-O1/non-O139 serogroups are most oftenresponsible for epidemic and pandemic cholera. This study used genotypic patterns of PCR-based detection of virulence-associated and regulatory protein genes, along with phage typing, tocharacterize 86 V. cholerae strains. Thirty-eight of 53 O1 biotype El Tor strains harboured bothtcpA classical and tcpA El Tor genes, and three El Tor strains lacked the V. cholerae O1-specificgene (Vc-O1); three O139 strains contained both Vc-O1 and Vc-O139 genes and seven out often non-O1/non-O139 strains possessed the Vc-O1 gene. The latter strains all harboured thevirulence-associated genes ctxA, zot, ace, RS1, hlyA, ompU, rtxA and sxt. Two phage types, T27and T25, were predominant in strains from different geographical regions of India, whereas morevariation in phage susceptibility was observed for tetracycline-resistant strains from Kolkata.These results suggest that the pattern and distribution of virulence genes and phage types of V.cholerae are equally useful and discriminatory in tracing the origin of newly emerging strains.