The Safety of Oyster Consumption: Assessing Bacterial Concentrations and Antibiotic Resistance of Vibrio Species in Oysters from Georgia’s Coast

Some Vibrio spp. are commonly found in shellfish and pose threats to consumers of oysters. V. parahaemolyticus is the leading cause of seafood borne illness worldwide, while V. vulnificus can cause various life-threatening illnesses. As Georgia expands its oyster mariculture industry, it is imperative to monitor the safety of harvests. To address these concerns, we have assessed oyster safety via long-term quantification of bacterial loads in oysters and antibiotic resistance patterns in samples collected from Sapelo Island, GA and Brunswick, GA. Thus far, concentrations of V. parahaemolyticus have been observed to reach, or exceed, FDA regulations for safe consumption extending into harvesting season which normally is considered safe. Currently, V. vulnificus bacterial loads are being evaluated for possible temporal trends. Antibiotic resistance has been assessed by creating a lawn of fresh cultures on MHII agar with Liofilchem® MIC strips, incubating, then examining for resistance against Ampicillin and Ciprofloxacin based on CLSI standards for Vibrio spp.. Thus far, resistance to both antibiotics has been observed with V. parahaemolyticus over multiple time periods and collection sites. Currently, resistance of Ampicillin has been seen in some V. vulnificus samples. Both the high bacterial loads and presence of antibiotic resistance expose consumers to pathogens that may be more difficult to treat. Data collected and examined, to date, suggests that further research is necessary to draw conclusions about the safety of developing oyster mariculture on Georgia’s coast, and this work will hopefully provide a framework for the further evolution of the industry.