Objective:
Determine prevalence and diversity of pathogenic E. coli and Salmonella in watersheds with different land uses (urban/suburban, forested, animal agriculture) in the mid-Atlantic area. Measure airborne dissemination and survival of pathogenic bacteria and endotoxin from manures, compost, and wastewater treatment plant sludge. Evaluate methods combining immunological and genetic techniques for detection of water-borne pathogenic E. coli.

Approach:
Water samples from watersheds with different land uses (e.g., urban/suburban, animal agriculture, forested) will be analyzed for the presence of presumptive enterohemorrhagic E. coli or Salmonella strains using immunomagnetic and PCR methods. Presumptive pathogenic strains will be isolated using selective media and characterized for a range of of pathogenicity genes. Bioaerosols will be collected during land application of dairy manure solids, composted dairy solids, and lagoon liquids; liquid swine manure and dry poultry litter. Samples will analyzed for heterotrophic bacteria, Clostridium perfringens endospores, E. coli, salmonellae, Enterococcus, coliphage (bacterial viruses) and endotoxin. Survival rates of aerosolized Bacillus subtilis (tracer strain), Enterococcus faecium, nonpathogenic E.coli, Salmonella typhimurium, and MS-2 coliphage will be determined in environmental chambers simulating summer-time temperature, humidity, and radiation conditions. A biosensor, combining immunological and PCR techniques, will be developed for the detection of water-borne enterohemorrhagic E. coli (e.g., E. coli O157:H7).