Characterisation of Vibrio parahaemolyticus isolated from seafood products

Abstract

Vibrio parahaemolyticus is a gram-negative halophilic autochthonous bacterium in the coastal marine environments that occasionally is present in inland aquacultures and saltwater environments. It is found in the gut and on the surface of marine animals and may be accumulated by bivalves. The consumption of raw or undercooked contaminated seafood may cause human illness, this pathogen being a leading cause of food borne gastroenteritis. The pathogenicity of this bacterium is mainly associated with the possession of two haemolysins, thermostable direct haemolysin (TDH) and thermostable related haemolysin (TRH). Besides, a positive Kanagawa phenomenon (KP) and the production of urease have been described as markers to predict the potential pathogenicity of this microorganism. The aim of this work was to characterise selected strains of V. parahaemolyticus isolated from shellfish harvesting areas and imported seafood products for biochemical and physiological properties and presence of virulence factors. Isolates were assayed for biochemical properties, salt tolerance and identified according to the analytical profile index of API 20E and 20NE. Species identification was also assayed by PCR using primer sets for tlh and toxR. The detection of the haemolysin genes was performed by PCR using two sets of primers. Selected correctly sized amplicons were confirmed by sequencing. Isolates exhibited diverse analytical profiles and API 20NE yielded the higher percentage of identification. Most of the strains identification was confirmed by PCR results. Isolates trh-positive were detected. The obtained results indicate that pathogenic V. parahaemolyticus may be present in food/environmental samples and suggest that a health risk can be associated with their consumption.