Tracking the Source of Enteric Pathogens in Surface Waters

A model system will be developed combining the use of environmental sentinels, automated detection of fecal coliforms and Salmonella, DNA fingerprinting, antimicrobial resistance profiling and multiple chemical assays (e.g. stable isotope analysis) to identify the origin of fecal waste in surface waters. We will facilitate the adoption of these fecal waste detection techniques by developing (and offering) a course for shellfish sanitation workers employed by NSSP agencies in 23 states to introduce them to the analytic techniques needed to implement the fecal waste detection system.
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Objective 1: Develop protocols for tracing the origin of fecal waste in surface waters - The Asian clam (Corbicula flumenia) will be used as a monitoring sentinel in the proposed studies. Cohorts of 600 clams at 15 sites. Sentinel clams will be held at 5 sites in the Neuse River five sites in Marks Creek and Big Arm Creek and 5 sites in Muddy Creek in the Cape Fear River Basin. Clam and water samples will be periodically sampled and analyzed. At each sampling, seven composite samples of five animals will be analyzed for caffeine, fecal sterols, and stable isotopes. We will also attempt to isolate fecal coliforms and Salmonella sp. from each of the 35 individual clams. Salmonella isolates will be further characterized by DNA fingerprinting and an antimicrobial resistance profiling. Water and tissue samples will be examined for: 1) Salmonella sp. 2) caffeine and fecal sterols; 3. antibiotics; Antimicrobial susceptibility testing and pulsed field gel electrophoresis will be used to compare Salmonella spp. isolates obtained from different study sites. Geographic information system layers that reflect the location of newly installed residential septic systems and their distance from surface waters will be developed. Spatial data classes and layers will contain FGDC compliant metadata. Spatial modeling will focus on the use of spatial autocorrelation procedures to detect potential clusters and subsequent source and transport identification. Analysis will concentrate on source proximity cluster detection. <p> Objective 2: Develop a course for training shellfish sanitation workers to use the developed fecal waste monitoring protocols. A combined classroom and laboratory-based "short-course" will be developed for NSSP agency and other water quality monitoring personnel. Molluscan shellfish sold in the US are harvested from our coastal estuaries and sounds. However these surface waters routinely receive fecal waste of residential, municipal, agricultural and wildlife origin. State agencies in states from which shellfish are harvested and sold monitor surface waters to ensure that oysters and other shellfish are safe for human consumption. Current shellfish sanitation guidelines focus on curtailing harvesting from contaminated areas. rather than identifying the source of fecal contamination. The result, nationally more than 2.8 million coastal acres are closed to commercial fisherman and aquaculturists due to the presence of fecal waste. However, outbreaks of human gastroenteritis still occur each year. This multidisciplinary effort was initiated to develop protocols for tracing the origin of fecal waste in surface waters and help train shellfish sanitation workers to use the developed fecal waste monitoring protocols; We anticipate that the protocols developed for surface water monitoring will assist state agencies tasked with monitoring surface waters by improving the tools needed to more specifically identify the source of fecal waste entering surface waters. In this manner, it will help target mitigation activities and potentially help us reclaim numerous acres of coastal habitat as an aquaculture and fishing resource. Improved surface water monitoring should also help improve the overall safety of marketed molluscan shellfish products.