Occurrence of Vibrio parahaemolyticus in retailed seafood in The Netherlands

This study was conducted to determine the prevalence of Vibrio parahaemolyticus in seafood samples in The Netherlands. In total 200 seafood samples, including fish, shrimp, oyster and mussel, collected from the retail market in The Netherlands were examined for the occurrence of V. parahaemolyticus using both a cultural and a direct PCR-based method. Two different selective media, thiosulfate citrate bile salts agar (TCBS) and CHROMagar Vibrio (CV), were evaluated for their efficacy to isolate V. parahaemolyticus from seafood samples. The results showed that there were no differences among the two media to isolate V. parahaemolyticus from all seafood samples (P 0.05). Using the cultural method, V. parahaemolyticus was isolated from 16 (8%) and 27 (13.5%) samples, on TCBS and CV plates respectively. All the positive samples were mussels and oysters. Of the 43 isolates of V. parahaemolyticus (on TCBS and CV) obtained, none of the isolates was positive for the genes tdh or trh. The PCR-based method was performed at 0 (t=0), 6 (t=6), and 18 (t=18) hours after the enrichment step and allowed the detection of V. parahaemolyticus in 22 (11%) and 38 (19%) samples, with the DNA extracts prepared from the first enrichment (t=6 h) and the second enrichment (t=18 h) respectively. None of the samples were detected to be V. parahaemolyticus-positive when the DNA extracts were prepared from the sample homogenate before the enrichment step (t=0 h).