Potentially pathogenic vibrios associated with mussels from a tropical region on the Atlantic coast of Brazil

Mussels ( Perna perna ) harvested on the coast of Ubatuba, in three different stations in the State of São Paulo, Brazil, were examined for Vibrio spp. over a 1 year period. The ranges of most probable number (MPN 100 g^-1) were: Vibrio alginolyticus (<3–24000), V. parahaemolyticus (<3–24000), V. fluvialis (<3–1100), V. cholerae non-O1 (<3–23), V. furnissi (< 3–30), V. mimicus (< 3–9) and V. vulnificus (< 3–3). The highest incidence was observed for V. alginolyticus (92–100%), followed by V. parahaemolyticus (67–92%), V. fluvialis (34–67%), V. vulnificus (8–17%), V. furnissii (0–17%), V. mimicus (0–17%) and V. cholerae non-O1 (0–8%). Tests for virulence factors were positive in 34.1% of the vibrios in the rabbit ileal loop and 31.7% in the Dean test. Positive results in the Kanagawa test were obtained with 0.51% of V. parahaemolyticus strains. The mean values (MPN 100 g^-1) of faecal coliforms in mussels from the three regions varied from 1100 to 44000, and seawater collected at the same stations gave average values for faecal coliforms in the range 18–3300 MPN 100 ml^-1. These results highlight the potential risks of food poisoning associated with raw or undercooked seafood.