Analysis of major phenotypes and hemolysin-related genotypes of Vibrio parahaemolyticus isolates from clinical and seafood samples

Abstract:

Vibrio parahaemolyticus is a gram-negative，halophilic bacterium that inhabits the marine and estuarine environments. It is an important human pathogen causing gastroenteritis when raw or partially-cooked seafoods are consumed. Its pathogenicity is believed to be related to hemolysins such as thermostable direct hemolysin(TDH)，TDH-related hemolysin (TRH) and thermolabile hemolysin (TLH). PCR method was used to examine three different hemolysin genes in isolates from clinical and seafood samples in Zhejiang province. The tlh gene was found in all isolates. The tdh gene was positive in all eleven clinical strains but only in one out of a total of 42 seafood isolates. The Kanagawa phenomenon was positive for all tdh-positive isolates. None of the isolates was positive for the trh gene. The urease test was negative for all isolates. Thus，it was assumed that the urease gene could be linked with trh gene. Further research is required to examine the relationship between low prevalence of the major virulence factor TDH and the high incidence of foodborne V. parahaemolyticus infections，and its pathogenesis.

Key words:Vibrio parahaemolyticus; hemolysins related genes; phenotypes