Rischio igienico sanitario associato al consumo dei molluschi eduli lamellibranchi (M.E.L)

Seafood represents a very broad category of food and is a major source of protein in the human diet. The increase of its consumption and the epidemiological data confirm the role of seafood (especially shellfish) as a carrier of foodborne toxinfections and has brought the need for a higher monitoring level and an increase of the studies of their microbiological characteristics. Edible Lamellibranch Molluscs (M.E.L) are frequently involved in food poisoning outbreaks of outstanding severity, due to the fact that they are filter-feeding animals which tend to accumulate any toxic substances or microorganisms already present in their environment. In the context of food security, the main target is to ensure food health by fulfilling specific hygiene requirements and by means of monitoring activities on shellfish conducted on the production chain of mussels and within their own environment. Microbiological eligibility for human consumption (Reg CE 1441/2007) is based on only two fecal contamination bacteriological parameters (Escherichia coli, Salmonella spp) and does not provide the identification of other microorganisms which are naturally present within the marine environment and potentially pathogenic such as those belonging to the genus Vibrio. In accordance with the data provided by the Centre of Disease Control (USA), food poisoning linked to the consumption of shellfish is mainly related to (20%) enteric viruses (Corraine et al., 2007), hepatitis A virus (HAV), norovirus (NV), and marine environment pathogens, such as Vibrio spp, whereas faecal bacteria (Salmonella spp. and Escherichia coli) account just for 4% of the total (Serracca et al., 2007) (Lipp EK, Rose JB, 1997). In order to assess the hygienic quality and health of M.E.L (mussels, clams and oysters) bred in Sardinia, both parameters required by law (Escherichia coli, Salmonella spp) and Vibrios of major public health interest have been investigated in this study. Within the 440 examined samples, 40% contained potentially harmful Vibrios species to human being, while only in 6.4% of the samples, the levels of Escherichia coli were above the Italian legal limit and only within one sample, Salmonella spp was isolated. An interconnection between the presence of micro-organisms of fecal origin and potentially harmful Vibrios to human health was not detected. Vibrio bacterial strains have been identified by means of biochemical techniques. Vibrio cholerae strains have been processed through the use of serological and molecular identification techniques and their toxigenic properties have been evaluated by PCR assay (search for the toxin CT and gene for the toxin NAG-ST). Overall, 14 strains of Vibrio cholerae were isolated which were found to be non-O1 and non-O139 Vibrio cholerae (NCVs) and therefore unable to give epidemic cholera. No strain was found to be producing CT and NAG-ST toxins.