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ARS Home » Midwest Area » Bowling Green, Kentucky » Food Animal Environmental Systems Research » Research » Publications at this Location » Publication #319281
Title: Strain diversity in the fecal indicator Escherichia coli: implications for its use as a produce pathogen surrogate

Author
item Cook, Kimberly - Kim
item GIVAN, ETHAN - Western Kentucky University
item TAYLOR, RITCHIE - Western Kentucky University

Submitted to: Kentucky Water Resources Research Institute Symposium
Publication Type: Proceedings
Publication Acceptance Date: 3/8/2015
Publication Date: 3/9/2015
Citation: Cook, K.L., Givan, E., Taylor, R. 2015. Strain diversity in the fecal indicator Escherichia coli: implications for its use as a produce pathogen surrogate. Kentucky Water Resources Research Institute Symposium. 49-50.

Interpretive Summary: One of the challenges in protecting the public against water and foodborne illness is understanding routes of contamination. One suspected route of food contamination is irrigation water. Surface water and ground water sources are often utilized for the irrigation of crops, and fresh produce in particular. Escherichia coli are widely used as fecal indicator bacteria (FIB) and as a surrogate for pathogens for water quality and food safety research. Using E. coli as a surrogate for produce pathogens should aid in research to understand the sources of contamination and how these pathogens persist in the water, soil and on plant surfaces. In this study E.coli isolates, the produce related pathogens Salmonella, Listeria, E. coli O157:H7 and a common quality control E.coli strain (EC 25922) were evaluated for factors that have been commonly linked to the survival and transmission of produce associated pathogens. Isolates were found to be genotypically and phenotypically diverse. Some isolates behaved more similarly to human pathogens associated with produce than do commonly used quality control strains. Using these data, and continued characterization of the isolates, isolates will be selected for future greenhouse experiments. e. This research will provide science based information on the differences in E. coli isolates from multiple environmental sources, the selection of enhanced produce pathogen surrogates, and the potential of produce contamination via contaminated irrigation water.

Technical Abstract: Contamination of food and water by pathogens is a substantial public health issue in the United States. One of the challenges in protecting the public against water and foodborne illness is understanding the routes of contamination. One suspected route of food contamination is irrigation water. Surface water and ground water sources are often utilized for the irrigation of crops, and fresh produce in particular. Escherichia coli are widely used as fecal indicator bacteria (FIB) and as a surrogate for pathogens for water quality and food safety research. Using E. coli as a surrogate for produce pathogens should aid in research to understand the sources of contamination and how these pathogens persist in the water, soil and on plant surfaces. A key step in using E. coli as a pathogen surrogate is to understand how this organism varies in the environment relative to pathogens so that the most representative surrogate can be selected. In this study 63 E. coli isolates were selected from a pool of 1,346 isolates previously taken from poultry, swine, dairy, and agriculturally impacted surface water sources (Cook et al, 2011). These 63 environmental E.coli isolates, the produce related pathogens Salmonella, Listeria, E. coli O157:H7 and a common quality control E.coli strain (EC 25922) were evaluated for factors that have been commonly linked to the survival and transmission of produce associated pathogens. Isolates were found to be genotypically and phenotypically diverse. Some isolates behaved more similarly to human pathogens associated with produce than do commonly used quality control strains. Using these data, and continued characterization of the isolates (carbon source utilization, genotypic data, soil and lettuce adhesion), isolates will be selected for future greenhouse experiments. These isolates will then be applied to soil and lettuce leaf substrates via spray or drip irrigation water, and isolate survival will be monitored over time. This research will provide science based information on the differences in E. coli isolates from multiple environmental sources, the selection of enhanced produce pathogen surrogates, and the potential of produce contamination via contaminated irrigation water.