Attachment of Salmonella Typhimurium to Fish Surfaces from a Suspension in Seawater and the Effect of Subsequent Washing

Abstract

ackground: Salmonella contamination of seafood is an important consumer health concern. Anthropogenic contamination of coastal-marine water is an important source of seafood contamination with Salmonella. In this study, we aimed to investigate the extent of Salmonella attachment when fish is exposed to contaminated seawater and also, the effect of washing on the removal of Salmonella attached to fish surface. Methods and Findings: Bombay duck (Harpadon nehereus) fish was dipped in seawater artificially contaminated with 5 log CFU/ ml Salmonella Typhimurium for 30, 45 and 60 seconds and the number of bacteria present on the fish surface was quantified by surface plating. Separately, the effect of rinsing Salmonella-contaminated fish for 30, 45 and 60 seconds on the removal of Salmonella from the fish surface was investigated. The results showed attachment of bacteria in significant numbers, in the range of 3.6 – 4.16 log CFU/g, within 60 seconds of exposure to Salmonella-contaminated seawater. However, no significant reduction in the Salmonella counts was observed after 30 to 60 seconds of rinsing of fish in freshwater. Conclusion: The results suggest that Salmonella Typhimurium can readily attach to the fish surface from a seawater medium and resist detachment by routine washing procedures.