Comparative Analysis of Bacterial Contamination in Three Species of Commercially Sold Oysters in Mindanao, Philippines

Since oysters are filter feeders, they collect harmful bacteria from their environment, which can be a serious health risk when eaten raw. Commercially sold oysters (Magallana bilineata) from Pagadian City, (Magallana gigas) from Dapitan City, and (Magallana spp.) in Ozamiz City were collected and utilized in the study to measure and compare the levels of bacterial contamination across these locations. This study used a descriptive-comparative research design to determine and compare the levels of bacterial contamination in commercially sold oysters from public markets and vendors. A total of eighteen kilograms of oyster samples were collected during the dry season from public markets and vendors and processed using convenience sampling. Standard microbiological techniques that included extraction, homogenization, isolation, and biochemical testing of the oyster were applied. The results showed that oysters from Pagadian City have the highest Vibrio spp. microbial load among the three locations, with an average total Vibrio spp. count of 6.31x10¹⁰ CFU/g and an average total Salmonella spp. count of 3.83x10¹⁰ CFU/g, Dapitan City has an average total Vibrio spp. count of 6.04x10¹⁰ CFU/g and the highest average total Salmonella spp. count of 4.47x10¹⁰ CFU/g, whereas Ozamiz City oysters have the least, at 5.02x10¹⁰ CFU/g and 2.97x10¹⁰ CFU/g, respectively. Pagadian City oysters showed the highest presence of Vibrio parahaemolyticus of the three locations. Statistical analysis revealed no significant difference in bacterial contamination across the three areas, which have p-values for both variables exceeding 0.05. The reduction of the microbial load and proper processing of oysters are essential in maintaining the health and safety of consumers.