Kanagawa-negative, tdh- and trh-positive Vibrio parahaemolyticus isolated from fresh oysters marketed in Fortaleza, Brazil.

Between October 2008 and June 2009, 15 samples of 10 live oysters each (Crassostrea rhizophorae) measuring 8.31-10.71 cm were purchased from a restaurant on the seashore of Fortaleza, Brazil. The Vibrio count ranged from 75 (estimated) to 43,500 CFU/g. Fourteen species were identified among the 56 isolated Vibrio strains, with V. parahaemolyticus as the most prevalent. Two of the 17 V. parahaemolyticus strains were urease-positive and tdh- and trh-positive on multiplex PCR, but neither produced β-hemolysis halos in Wagatsuma agar. Thus, fresh oysters served in natura in Fortaleza, Brazil, were found to contain Vibrio strains known to cause gastroenteritis in humans.