Prevalence of Salmonella and Edwardsiella spp. in Nile Tilapia (Oreochromis niloticus) sold in some retail fish markets in Tehran, Iran

Salmonella spp. and Edwardsiella spp. are major zoonotic pathogens associated with seafood, responsible for foodborne illnesses and significant public health risks. This study investigated their prevalence in Nile tilapia (Oreochromis niloticus) sold in retail fish markets in Tehran, Iran. A total of ۱۰۸ samples were collected in autumn ۲۰۲۴, including ۶۸ fresh whole fish, ۲۴ imported frozen fillets from the main market, and ۱۶ fresh samples from retail outlets. Two skin swabs were taken from each fish and analyzed according to ISO ۶۵۷۹-۱:۲۰۱۷ standards, using selective enrichment, bacteriological plating, and biochemical confirmation. Initial screening suggested Salmonella in ۴۸ samples (۴۴.۴%) and Edwardsiella in ۸ (۷.۴%). Confirmatory testing identified Salmonella spp. in ۸ samples (۷.۴%): ۴ from frozen fillets and ۴ from fresh retail fish. Edwardsiella spp. was confirmed in ۴ samples (۳.۷%), all originating from frozen fillets. Statistical analysis showed a significant difference in Edwardsiella contamination between fresh and frozen samples (p = ۰.۰۱۴۷). Salmonella contamination also differed significantly between the main market and other retail sources (p = ۰.۰۰۲۶). These findings suggest contamination may be linked to poor packaging and non-specialized handling in retail settings. As tilapia is increasingly consumed raw or undercooked, routine microbial monitoring is necessary to protect food safety.

کلیدواژه ها:

Salmonella ، Edwardsiella ، Nile tilapia ، Tehran ، Fish markets