Prevalence of Escherichia coli and Salmonella spp. in mussels (Mytilus galloprovincialis) and serotyping of Salmonella spp. in Zenata and Mansouria regions of Morocco

Due to their immobile nature and filter-feeding habits, which enable biological particles to accumulate in their tissues, mussels are recognized as vectors of foodborne diseases. Consuming these shellfish uncooked or partly processed might result in food poisoning because of accumulated bacteria originating from the culture environment and unhygienic handling. The present study aimed to assess the presence of Salmonella and Escherichia coli as well as to biochemically and serotypically confirm Salmonella spp. in mussels (Mytilus galloprovincialis) taken from two locations in Morocco: Zenata and Mansouria. A total of 90 mussel samples were collected from October 2022 to August 2023. Two methods were employed in this study: AFNOR NF EN ISO 6579-1 (2017) for the detection of Salmonella spp., and the most probable number method (MPN) using Norm ISO/TS 16649–3 (2017) for E. coli. The number of E. coli varied between 0.2/100 g and 1.7 x 103/100 g of mussels. The percentage of Salmonella spp. detected in mussel samples was 4,4%. Further analysis revealed the identification of two distinct Salmonella serotypes, namely S. kentucky (1 isolate) and S. Typhimurium (3 isolates). This research highlights the potential risks to public health due to the presence of pathogenic bacteria in mussels from two regions of Morocco where shellfish farming and coastal tourism are significant contributors to the local economy.