Vibrio cholera contamination of marine and aquatic products in Zhangzhou city

Objective To identify Vibrio cholera contamination of marine and aquatic products in Zhangzhou city as well as the bacterial types. Methods Smears were taken from the surface, gill and cloaca of marine and aquatic products sold in fisheries, markets and restaurants, which were directly inoculated into alkaline peptone water to allow bacterial growth. The resulting samples were streaked on gentamicin agar plates for isolation. Pure culture was drawn for staining microscopy. Slide agglutination tests were carried out using a mixture of Vibrio cholera and type-specific polyvalent, group O139 and monovalent sera, and positive strains were subject to tube agglutination and systematic biochemical identification. Conventional PCR was performed to identify the Vibrio cholera enterotoxin gene ctxA. The detection rates of Vibrio cholera were compared using the chi-square test. Results The Vibrio cholera-carrying rate in marine and aquatic products in Zhangzhou was 5.08% (26/512). Fifteen strains of Ogawa serotype and 11 of Inaba serotypes were found. The highest bacteria-carrying rate was found in frogs(25.00%,13/52). No ctxA-bearing strains were detected. After 6 to 8 hours of bacterial growth, the detection rate of Vibrio cholera was 0.78%, which increased to 2.34% after 18 to 24 hours of growth. The difference between the two bacterial growth times was significant (P0.05). The detection rate increased to 5.08% after a second growth from 2.34% of the first, which was significantly different (P0.05). Conclusion Vibrio cholera contamination of marine and aquatic products was fououdn in Zhangzhou city, entailing appropriate control measures to prevent the occurrence of cholera epidemics. Comparative experiments on the culture conditions of contaminated samples revealed that the optimum time for bacterial growth should be 18-24 h with a preferably additional growth.