Identification of Vibrio spp. Toxin Production in Oysters (Crassostrea virginica) from Georgia's Coast

Vibrio parahaemolyticus bacteria are frequently found in shellfish, including oysters, and are the leading cause of seafood-borne illness in the United States. As Georgia’s coastal region is looking to expand upon their current oyster mariculture industry, we assessed the presence of V. parahaemolyticus in oysters during the harvesting and non-harvesting seasons and investigated if these bacteria possess hemolytic toxins. This study focuses on 4 sites on Sapelo Island, which are located near areas of potential mariculture development. Oysters were collected in batches of ten every 8-10 weeks throughout 2023. Following collection, samples were homogenized and diluted in 0.9% normal saline before being plated on CHROMagar^TM (Vibrio specific agar) in order to identify the presence of Vibrio spp. To validate the results from the CHROMagar method of identifying V. parahaemolyticus, we sought to determine if the TDH and TRH toxins that cause seafood-borne illness by V. parahaemolyticus were present in our samples. To do so, an assay that targets specific genetic sequences of bacteria has been implemented to identify the seafood-borne illness toxins that were identified in bacteria by amplification of the specific toxin genes. In doing so, TDH and TRH toxin producing V. parahaemolyticus have been identified in samples we have collected from Sapelo Island. These results indicate that the collection sites around Sapelo Island are home to pathogenic V. parahaemolyticus resulting in an important emphasis on harvesting these oysters be limited to times when V. parahaemolyticus populations are at their lowest.