Vibrio virulence genes in fishes collected from estuarine waters in Italy.

AIMS

The aim of this study was to investigate the presence of Vibrio vulnificus and potentially pathogenic strains of Vibrio parahaemolyticus in mullets collected from estuarine environment in Italy.

METHODS AND RESULTS

Two hundred and ninety-five mullets were analysed by culture using the selective medium thiosulfate citrate bile salt sucrose agar, during a monitoring period of 2 years (2008-2009). Presumptive Vibrio colonies were initially identified by using biochemical tests, and strains identified as V. parahaemolyticus and V. vulnificus were subsequently examined by PCR for the presence of species-specific and virulence genes (toxR, trh, tdh and vvh). V. parahaemolyticus was found in 55% (162/295) of fishes and V. vulnificus in 1% (3/295) with a higher presence in summer months. The trh+/tdh- strains were detected in 16% (47/295) of samples and only one strain resulted trh+/tdh+. One of the V. parahaemolyticus trh+ strains isolated belonged to the O1:KUT (K untypeable), a serotype recently associated to gastroenteritis in Italy.

CONCLUSIONS

This is the first report demonstrating a high percentage of potential pathogenic V. parahaemolyticus trh+ strains in estuarine fishes of the Mediterranean area.

SIGNIFICANCE AND IMPACT OF THE STUDY

These findings indicate the potential human health risk associated with the presence of pathogenic Vibrio spp. in wild fishes.