Mesophilic Aeromonas spp. isolated from ready-to-eat seafood: Insight into antimicrobial resistance, virulence factors, and growth kinetics in food

Abstract

With the current trend of consuming fresh, natural, and convenient food, ready-to-eat (RTE) seafood, such as sushi, sashimi, or cold-smoked fish products, has gained popularity. Increased consumption of RTE seafood poses food safety challenges in food industry, since RTE seafood are consumed without further cooking process that eliminate or reduce to an acceptable level of microorganisms of concern. Particularly, there is a growing concern over mesophilic Aeromonas as a microbiological hazard in connection with consumption of RTE seafood. In addition, due to the ubiquitous nature of Aeromonas in aquatic environments and their ability to acquire and exchange genetic material, they might play a role in the emergence and transmission of antimicrobial resistance in the food chain. However, there is limited knowledge on antimicrobial resistance, virulence factors, and growth kinetics in food among Aeromonas spp. when present in RTE seafood. Therefore, the aim of the PhD work is establishing more knowledge on Aeromonas in RTE seafood to understand their role as foodborne pathogens and in the spread of antimicrobial resistance.

In this work, occurrence of mesophilic Aeromonas in RTE seafood was confirmed based on the sampling of RTE seafood available on the Norwegian market. Growth kinetic studies of selected Aeromonas strains from RTE seafood showed that mild processing factors that often applied in the production of RTE seafood may not guarantee the total inhibition of Aeromonas. In addition, most of Aeromonas strains were potentially pathogenic by carrying multiple virulence factors. Moreover, multidrug resistant Aeromonas strains were prevalent in RTE seafood, and some of the strains may act as a vector of transferring antimicrobial resistance genes in their mobile elements to other bacterial species. In conclusion, the present study suggests Aeromonas present in RTE seafood must be considered as a risk factor to the frequent consumers of RTE seafood, and consumption of RTE seafood contaminated with multidrug resistant Aeromonas is likely a potential transmission route of antimicrobial resistance from aquatic animals or environments to humans.