Prevalence, serotyping and molecular characterization of Vibrio parahaemolyticus in mussels from Italian growing areas, Adriatic Sea.

The aims of this study were to investigate the prevalence of total and pathogenic Vibrio parahaemolyticus strains in Italian mussels from different geographical areas of the Adriatic Sea and to determine their serotypes, toxigenic profiles and pandemic potential. Out of 559 samples analysed during 2007, 65 (11.6%) were positive for V. parahaemolyticus. None of the isolates had the genes for thermostable direct haemolysin (tdh) and pandemic marker (toxRS), while five strains (7.7%) had that for TDH-related haemolysin (trh). Regarding geographical location of the toxigenic strains, three were from the Adriatic coast of Puglia, one from Veneto, and one from the Marches. The trh-positive V. parahaemolyticus isolates from Puglia belonged to O1:KUT (2/3) and O1:K37(1/3) serotypes, the trh-positive isolate from the Marches to OUT(O untypeable):KUT serotype, and that from Veneto to O3:KUT. The prevalence of trh-positive V. parahaemolyticus obtained from mussels in this study was higher respect to that reported in previous studies from other European and Extraeuropean countries. The Health Authorities should be more aware of the epidemiological role of environmental V. parahaemolyticus in local food-borne diseases, and increase the microbial surveillance on these microorganisms isolated from shellfish.