Category Archives: Vibrio alginolyticus

Research – Whole genome sequencing reveals great diversity of Vibrio spp in prawns at retail

Microbiology Research

Food Illness

Consumption of prawns as a protein source has been on the rise worldwide with seafood identified as the predominant attributable source of human vibriosis. However, surveillance of non-cholera is limited both in public health and in food. Using a population- and market share-weighted study design, 211 prawn samples were collected and cultured for spp. Contamination was detected in 46 % of samples, and multiple diverse isolates were obtained from 34 % of positive samples. Whole genome sequencing (WGS) and phylogenetic analysis illustrated a comprehensive view of species diversity in prawns available at retail, with no known pathogenicity markers identified in and . Antimicrobial resistance genes were found in 77 % of isolates, and 12 % carried genes conferring resistance to three or more drug classes. Resistance genes were found predominantly in , though multiple resistance genes were also identified in and . This study highlights the large diversity in derived from prawns at retail, even within a single sample. Although there was little evidence in this study that prawns are a major source of vibriosis in the UK, surveillance of non-cholera is very limited. This study illustrates the value of expanding WGS surveillance efforts of non-cholera Vibrios in the food chain to identify critical control points for food safety through the production system and to determine the full extent of the public health impact.

Research – Effect of food matrix type on growth characteristics and hemolysin production of Vibrio alginolyticus

Journal of Food Protection

Food Illness

The growth and hemolysin production of two V.   alginolyticus  strains (HY9901 and ATCC17749T) at 30 °C in briny tilapia, shrimp, scallop, oyster, pork, chicken, freshwater fish and egg fried rice were investigated. Bacterial counts were enumerated by plate counting. Hemolysin production was evaluated by blood agar and hemolytic titer tests. The two V.   alginolyticus  strains displayed similar growth and hemolysin production patterns in the foods. Based on the goodness of fit primary model statistics (R 2 , MSE, BF, AF), the modified Gompertz model was a better fit to V.   alginolyticus  growth in foods than the logistic model. Growth kinetic parameters of V.   alginolyticus  displayed a higher μ max and shorter λ in briny tilapia > shrimp > freshwater fish > egg fried rice > scallop > oyster > chicken > pork. It was notable that the V.   alginolyticus  counts were similar at the stationary phase, with no significant growth behavior difference between raw and cooked foods. Significantly higher (p < 0.05) thermostable direct hemolysin (TDH) activity was produced by V.   alginolyticus  in briny tilapia > freshwater fish > shrimp > chicken > egg fried rice > scallop > oyster > pork. But the hemolytic titer was not consistent with the TDH activity, being significantly higher (p < 0.05) in briny tilapia > egg fried rice > shrimp > freshwater fish > chicken > scallop > oyster > pork. Contrary to current belief, V.   alginolyticus  displayed a higher hemolysin production in some non-seafoods (freshwater fish, egg fried rice and chicken) than in scallop or oyster. This is the first report of growth and toxicity of V. alginolyticus  in different food matrices and confirmation that some non-seafood contaminated with V. alginolyticus  can be even more pathogenic. This study will enhance the awareness of non-seafood safety and improve the V.   alginolyticus  risk assessment accuracy.