Survey of clinical and environmental Vibrio parahaemolyticus isolates for putative virulence factors and cytotoxicity of extracellular products to a CHO-K1 cell line

Abstract

Abstract The halophilic bacterium Vibrio parahaemolyticus is widely distributed as a natural inhabitant of marine and estuarine environments throughout the world. Many strains are avirulent in humans, but virulent strains are the causative agent of gastroenteritis acquired through consumption of contaminated raw or undercooked seafood. Therefore, it is likely that most V. parahaemolyticus isolates from the marine environment are harmless to humans. Virulent isolates are difficult to differentiate from the majority of avirulent environmental isolates. A total of 55 V. parahaemolyticus isolates (22 clinical, 31 environmental and 2 reference strains) were examined for the carriage of plasmids, whole cell protein profiles; their haemolytic, lipase, phospholipase, protease and urease activities; and the cytotoxicity of their extracellular products (ECPs). Analysis of variance for V. parahaemolyticus isolates showed that Kanagawa haemolysis, phospholipase, protease and urease activities were significantly related to cytotoxicity as assayed by measuring relative extracellular lactate dehydrogenase as an indicator of damage of CHO-K1 cells. The difference between the mean values of cytotoxicity of ECPs of clinical and environmental isolates was significant at a p value of < 0.05.