Reduction of infection risk mediated by co-culturing Vibrio parahaemolyticus and Listeria monocytogenes in refrigerated cooked shrimp.

BACKGROUND: Vibrio parahaemolyticus and Listeria monocytogenes are seafood pathogens of public health significance, and predictive models are effective tools for quantitative microbial risk assessment of these pathogens. However, most current predictive models are based on growth of single strains in broth cultures, and interactions of two or more bacteria in a food matrix can skew the outcomes of the predictions. Therefore, the impact of V. parahaemolyticus and L. monocytogenes when co-cultured and in monoculture on cooked shrimp in cold storage was investigated.

RESULTS: The results indicated that L. monocytogenes co-cultured with V. parahaemolyticus exhibited reduced growth and longer lag phase at 4 °C and 10 °C. V. parahaemolyticus exhibited similar behavior when co-cultured with L. monocytogenes at 4 °C (death rate K =  - 0.67 log10 CFU g-1 day . The death rate K at 10 °C when V. parahaemolyticus co-cultured with L. monocytogenes was -1.62 log10 CFU g-1 day-1 . There was no significant reduction of growth in monoculture experiments.

CONCLUSION: This study has revealed that interaction of V. parahaemolyticus and L. monocytogenes should be considered when quantifying risks posed by these pathogens during consumption of seafood products. © 2018 Society of Chemical Industry.