Microbial Quality of Oysters and Oyster Growing Waters in Chatham County

Fecal indicator bacteria (FIB), are commonly used to detect microbiological quality of shellfish. Total coliform and fecal coliform are indicator bacteria for food and water contamination developed by the Food and Drug Administration (FDA) under the National Shellfish Sanitation Program (NSSP) to detect enteric pathogens in recreational and shellfish-harvesting waters. Georgia follows the NSSP 2013 guidelines for routine monitoring of shellfish-harvesting waters. In Chatham County, Georgia there are a total of 17 shellfish growing areas and only 11 sites are classified as approved shellfish waters according to NSSP standards. The purpose of this study is to detect and identify the presence of fecal contamination within shellfish harvesting waters in Chatham County. Water and oyster samples were collected monthly from three shellfish growing sites (1223, 1224, and 1338). Culture based (m-Endo agar and Colilert) and molecular methods quantitative polymerase chain reaction (qPCR) methods were used to detect FIB in water and oysters. Approved waters must meet the 14/43 standard which requires the geometric mean of fecal coliform concentration to fall below the limit of 14 most probable number (MPN)/100 ml. The highest geometric mean for total coliform, fecal coliform, and Escherichia coli was detected in 1338 (1120 CFU/100 ml, 199 CFU/100 ml, and 133 CFU/100 ml) respectively. This site is located in an enclosed area with low circulation and under the influence of runoff and urbanization. The other two sites met the 14/43 standard. Further analyses using microbial source tracking will determine if the sources of pollution at this site are caused by humans, wildlife, or both.