Improved method for detection of Vibrio parahaemolyticus in seafood

We have developed a new, effective procedure for detecting Vibrio parahaemo lyticus in seafoods using enrichment and plating onto a chromogenic agar me dium. Samples were cultured in salt Trypticase soy broth, which is a nonsel ective medium, and then a portion of the culture was cultured with salt pol ymyxin broth, which is a selective medium for V parahaemolyticus. This two- step enrichment was more effective than the one-step enrichment in salt pol ymyxin broth alone. The enrichment cultures were then plated onto a new chr omogenic agar containing substrates for beta-galactosidase. The V. parahaem olyticus colonies developed a purple color on this growth medium that disti nguished them from other related bacterial strains. V. parahaemolyticus was isolated more frequently from naturally contaminated seafood samples using the chromogenic agar than thiosulfate citrate bile salts sucrose agar medi um, which is currently used for the isolation of V. parahaemolyticus. Our f indings suggest that this new enrichment and isolation scheme is more sensi tive and accurate for identifying V. parahaemolyticus in seafood samples th an previously used methods.