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Sixty-six strains of Vibrio parahaemolyticus belonging to 14 serotypes were isolated from hospitalized patients in Dhaka, Bangladesh, from January 1998 to December 2000. Among these, 48 strains belonging to four serotypes had the pandemic genotype and possessed the tdh gene. A marker (open reading frame ORF8) for a filamentous phage previously thought to correspond to the pandemic genotype was found to have a poor correlation with the pandemic genotype

We investigated the prevalence of Shiga toxin-producing Escherichia coli (STEC) in hospitalized diarrhea patients in Calcutta, India, as well as in healthy domestic cattle and raw beef samples collected from the city's abattoir. Multiplex polymerase chain reaction using primers specific for stx1 and stx2 detected STEC in 18% of cow stool samples, 50% of raw beef samples, and 1.4% and 0.6% of bloody and watery stool samples, respectively, from hospitalized diarrhea patients. Various virulence genes in the STEC isolates indicated that stx1 allele predominated. Plasmid-borne markers, namely, hlyA, katP, espP, and etpD, were also identified. Bead enzyme-linked immunosorbent assay and Vero cell assay were performed to detect and evaluate the cytotoxic effect of the Shiga toxins produced by the strains. STEC is not an important cause of diarrhea in India; however, its presence in domestic cattle and beef samples suggests that this enteropathogen may become a major public health problem in the future.

The genetic relatedness of 81 isolates of Vibrio parahaemolyticus was assessed by multilocus sequence typing. The strain with serotype O3:K6 emerged as a pandemic pathogen in 1996, with subsequent expansion to include strains having serotypes O1:KUT, O4:K68, and O1:K25. Sequence data from gyrB, recA, dnaE, and gnd revealed that 16 distinct serogroups isolated prior to the pandemic were highly variable and only isolates of serogroup O3:K6 shared two alleles with the pandemic strains. The pandemic strains regardless of serotype were clonal, with 51 of 54 isolates having the identical allelic profile (AP). Serotype alone did not adequately define a pandemic strain: among O1:KUT strains tested, seven strains with the identical pandemic AP carried previously described pandemic markers, while five nonpandemic strains had five distinct APs. Our sequence data provide strong molecular support for the clonal origin of pandemic V. parahaemolyticus O3:K6 and suggest that strains within such a clonal group may acquire previously identified serotypes.