Indigenous Vibrio cholerae strains from a non-endemic region are pathogenic

Abstract

Of the 200+ serogroups of Vibrio cholerae, only O1 or O139 strains are reported to cause cholera, and mostly in endemic regions. Cholera outbreaks elsewhere are considered to be via importation of pathogenic strains. Using established animal models, we show that diverse V. cholerae strains indigenous to a non-endemic environment (Sydney, Australia), including non-O1/O139 serogroup strains, are able to both colonize the intestine and result in fluid accumulation despite lacking virulence factors believed to be important. Most strains lacked the type three secretion system considered a mediator of diarrhoea in non-O1/O13 V. cholerae. Multi-locus sequence typing (MLST) showed that the Sydney isolates did not form a single clade and were distinct from O1/O139 toxigenic strains. There was no correlation between genetic relatedness and the profile of virulence-associated factors. Current analyses of diseases mediated by V. cholerae focus on endemic regions, with only those strains that possess particular virulence factors considered pathogenic. Our data suggest that factors other than those previously well described are of potential importance in influencing disease outbreaks.

A genomic island in Vibrio cholerae with VPI-1 site-specific recombination characteristics contains CRISPR-Cas and type VI secretion modules

“…The non-O1/O139 V. cholerae S12 strain was isolated from the Georges River (Sydney, Australia) in 200927 and routinely cultured on Luria-Bertani medium at 37 °C. The whole genome of V. cholerae S12 was paired-end sequenced at the Wellcome Trust Sanger Institute (Hinxton, UK) using Illumina HiSeq 2000 (San Diego, CA, USA) from DNA extracted using the Wizard Genomic DNA Purification Kit (Promega, Madison, WI, USA).…”

A genomic island integrated into recA of Vibrio cholerae contains a divergent recA and provides multi‐pathway protection from DNA damage

“…Identification of a novel genomic island in V. cholerae S24 containing recA S24 is an environmental, non-O1/O139 V. cholerae strain isolated from Georges River in Sydney, Australia, as described in a previous study (Islam et al, 2013). It was noted during multilocus sequence analysis of housekeeping genes adk, gyrB, mdh and recA using primers designed to amplify the V. cholerae S24 recA, (designated here recA S24), that a product of ∼ 1.5 kb was identified instead of the expected ∼ 850 bp.…”

“…To determine whether the RME was capable of translocating from the genome of V. cholerae S24 into a new location, a vector (pOriVn 700 ‐ recA S22 ; see Fig. A) containing the recA gene from a closely related strain of V. cholerae S24, strain S22 (Islam et al ., ), was introduced into V. cholerae S24 by conjugation. Here, the RME is expected to excise from the genome of V. cholerae S24 and insert into recA S22 present on pOriVn 700 ‐ recA S22 .…”

Vibrio cholerae non-O1 in bivalve mollusks harvesting area in Bahia, Brazil

“…However serogroups non-O1 and non-O139 of environmental origin can be considered strains without risk, it is known that the aquatic environment can serve as a reservoir for the emergence of pathogenic strains from populations not pathogenic, due acquisition of genetic mobile materials, thus creating new pandemic strains (Islam et al, 2013).…”