Seasonal abundance of Vibrio cholerae non O1/non O139 chxA plus in oysters harvested in a coastal lagoon of Mexico's Gulf coast: A seafood safety risk concern

The potential hazards associated with waterborne pathogens in shellfish differ among regions and vary according to environmental conditions. This study evaluated the influence of water temperature, salinity, chlorophyll a, pH, and turbidity on the seasonal density of Vibrio cholerae non-O1/non-O139 ompW and pathogenic ctxA and chxA in Mandinga Lagoon American oysters (Crassostrea virginica). V. cholerae nonO1/non-O139 ompW+ and chxA+ prevalences were significantly high in summer (7.0%) and during the winter season (4.5%) and all ompW + isolates were confirmed chxA+. The highest mean V. cholerae nonO1/non-O139 ompW+/chxA+ densities were observed during summer (11.53/2.29 MPN/g bank A) and fall (97.76/5.19MPN/g bank B) than those detected in other seasons. Cholera toxin ctxA was not detected throughout the study period. V. cholerae non-O1/non O139 ompW+ density was related to the influence of temperature - chlorophyll a and to salinity chlorophyll a (R-2 = 0.505, P = 0.015), and V. cholerae non-O1/non O139 chxA+ density was related to the influence of temperature turbidity and to salinity chlorophyll a (R-2 = 0.400, P = 0.021). As the ChxA toxin is a lately discovered virulence factor that induces pathogenicity in humans, our findings provide a perspective regarding the environmental conditions regulating the dynamic of pathogenic V. cholerae non-O1/no-O139 chXA+ occurrence in tropical regions and its significance in the preventive measures required to enhance the safety of raw oysters in order to protect consumer health. (C) 2015 Elsevier Ltd. All rights reserved.