At the interface with the marine environment, oysters can filter more than 200 liters of water per day. This filtration process enables them to concentrate human-pathogenic bacteria present in coastal waters, revealing the surrounding contamination. However, detecting these bacteria is not an easy task, making it crucial to develop effective identification tools. This requires a better understanding of these pathogens, so we propose to characterize enteric bacteria isolated from shellfish. Human-pathogenic enteric bacteria primarily originate from the gastrointestinal tract of mammals. This animal reservoir poses a significant danger because fecal matter, present in livestock effluents and wastewater, can contaminate watersheds, coastal areas, and shellfish production zones. Understanding the fate of these pathogens is a key research question, as their presence in shellfish indicates environmental contamination stemming from human activities. Today, Salmonella and Campylobacter are the two main bacterial genera responsible for diarrheal diseases, and they can also contaminate shellfish.

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Campylobacter are pathogenic bacteria for humans and represent the fourth leading cause of gastroenteritis worldwide, especially in developed countries. Ninety percent of infection cases are caused by Campylobacter jejuni and are linked to the consumption of contaminated food, particularly poultry meat. The possible contamination of shellfish by Campylobacter lari and jejuni has also been demonstrated (Rincé et al., 2018). Campylobacter have been relatively understudied due to their difficulty in cultivation. The microaerobic culture and viable but non-cultivable state of these bacteria can pose challenges for their isolation from shellfish. Subtyping methods are available to study the population structure and origins of strains, primarily based on Multi-Locus Sequence Typing (MLST) after isolation.

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