Enhancing Food Safety Through Control of Food-Borne Disease Agents

NON-TECHNICAL SUMMARY: Control of foodborne pathogens in the food production environment is a useful method to enhance food safety. This project will provide information on how bacterial pathogens survive and persist in the environment and how these organisms are subsequently transmitted to animals. The goal of the research is to identify ways to prevent or reduce food-animal infection with bacteria that pose hazards to the food supply.

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APPROACH: Traditional microbiological techniques and novel molecular methods to be integrated to provide the necessary tools to achieve the project objectives.

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PROGRESS: 2003/10 TO 2006/09
Objectives: 1) Determine the environmental factors that impact the survival and persistence of STEC in the farm environment and the transmission to animals; 2) Determine the role of wild animals in the dissemination of E. coli O157; 3) Determine the effect of dietary manipulation on the prevalence and magnitude of fecal excretion of foodborne pathogens. Both field studies and laboratory experiments have been conducted and are ongoing to achieve these aims. To ascertain the extent to which indistinguishable strains of Escherichia coli O157:H7 are shared between farms, and determine the potential sources contributing to the dissemination of this organism between farms, molecular characterization was performed on E. coli O157:H7 isolates recovered during a longitudinal study of 20 dairy farms in NE Ohio. Most restriction endonuclease digestion profiles (REDPs) were spatially and temporally clustered. However, four REDPs from multiple sources were found to be indistinguishable by pulsed-field gel electrophoresis (PFGE) between four pairs of farms. The geographical distance between farms which shared an indistinguishable E. coli O157:H7 REDP ranged from 9 km to 50 km, and the on-farm sources sharing indistinguishable REDPs included cattle feces, wild birds and free-stall bedding. In order to more precisely predict food safety risks, the fecal presence of foodborne pathogens among animals at slaughter must be correctly determined. Quantification of E. coli O157 is also desirable. The sensitivity of detection of E. coli O157 by both direct plating and immunomagnetic separation (IMS) was highly dependent upon the initial concentration of the target organism in the sample. Sensitivity of detection of E. coli O157 in bovine feces at low initial concentrations is very poor for both direct plating and IMS. Direct plating of dilutions of bovine feces can be used to determine the magnitude of fecal E. coli excretion among cattle excreting greater than 100 CFU/g.

IMPACT: 2003/10 TO 2006/09
Better tools are now validated for quantitative assessment of E. coli O157 in bovine manure. These tools, along with molecular epidemiology, have provided insight into the role of wildlife in disseminating E. coli O157 between farms. Control of E. coli O15 in wildlife may reduce bovine carriage of this pathogen and protect crops from contamination.