Incidence of highly genetically diversified Vibrio parahaemolyticus in seafood imported from Asian countries.

Vibrio parahaemolyticus is an important pathogen of humans and aquacultured animals, especially in Asian countries. In this study, we examined 686 samples of seafood imported from Hong Kong, Indonesia, Thailand and Vietnam for V. parahaemolyticus. V. parahaemolyticus was recovered from 315 (45.9%) samples. The incidence of V. parahaemolyticus in products from Hong Kong and Thailand was markedly higher than the incidence in products from Indonesia and Vietnam. The incidence rates in shrimp, crab, snail, lobster, sand crab, fish and crawfish were 75.8, 73.3, 44.3, 44.1, 32.5, 29.3 and 21.1%, respectively. None of the isolates possessed the hemolysin genes (tdh, trh). The chromosomal DNA of 121 randomly selected imported isolates and three local environmental strains was digested with SfiI and analyzed by pulsed-field gel electrophoresis (PFGE). These isolates were then grouped into 96 different but mostly unique PFGE patterns. After hierarchical cluster analysis, these patterns could be arbitrarily grouped into twenty-two PFGE types (type A to V). A wide range of PFGE types were identified in isolates from different origin. Moreover, the PFGE types were not specifically associated with the origin or kind of seafood. These results reveal the high genetic diversity in V. parahaemolyticus isolated from seafood.