Comparison of a fluorogenic assay with a conventional method for rapid detection of Vibrio parahaermolyticus in seafoods

A conventional method and a fluorogenic assay for the detection of Vibrio parahaemolyticus were compared. Among 29 seafood samples examined for the presence of V. parahaemolyticus, 17 samples harbored V. parahaemolyticus, and trypsinlike activity was noticed in 19 seafoods. The added fluorogenic substrate was cleaved in single samples of shrimp, turbo, and cuttlefish from which V. parahaemolyticus could not be isolated by the conventional method. Vibrio alginolyticus, in addition to V. parahaemolyticus, was found to exhibit intracellular trypsinlike activity. Trypsinlike activity in seafoods was observed after the most probable number for the initial density of V. parahaemolyticus-like organisms was found to have reached >10² per g. A V. parahaemolyticus inoculum at 10⁴ CFU/ml in arabinose-glucuronate medium was required to attain growth to l0⁶ CFU/ml, which is the level necessary for the release of detectable amounts of fluorescent compound from the added substrate.