Doctor of Philosophy (PhD)


School of Nutrition and Food Sciences

Document Type



Escherichia coli O157:H7 is an emerging food pathogen that was first identified as a cause of illness in 1982. According to CDC (The Center for Disease Control and Prevention) estimates, E. coli O157:H7 is responsible for about 73,000 illnesses, 2,000 hospitalizations and 60 deaths in the United States each year. Cattle are the principal reservoir of E. coli O157:H7. Contamination of feed and drinking water with cattle feces is an importance factor in the prevalence of infection in cattle which, in turn, results in contamination of food and the environment. Escherichia coli O157:H7 is a very persistent pathogen and has been shown to survive for long periods of time in the cattle farm environments. The purpose of this study was to test for the presence of E. coli O157:H7 in cattle water troughs of four cattle farms in Louisiana and also to study the survival and growth characteristics of different strains of E. coli O157:H7 in cattle water trough sediments using experimental microcosms. Escherichia coli O157:H7 can form biofilms on food contact surfaces and is responsible for several outbreaks caused due to cross-contamination in food processing plants. An additional objective of this study was to investigate the antimicrobial effects of cetylpyridinium chloride (CPC) against E. coli O157:H7 biofilms grown on stainless steel surfaces in different temperature and culture conditions. Results from this study showed an E. coli O157:H7 prevalence of 4.5% in the cattle water troughs. Survival studies showed variability in the growth of E. coli O157:H7 at different temperatures. Higher temperatures (25°C and 37°C) resulted in greater decrease of E. coli O157:H7 than at lower temperatures (5°C and 15°C), especially in the presence of natural microflora. It was also observed that the growth and survival of human E. coli O157:H7 isolates was significantly lower than environmental isolates at lower temperatures (5°C and 15°C). The biofilm study showed that <1.0% CPC was effective in inactivation of E. coli O157:H7 biofilms grown on stainless steel in all treatment conditions.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Marlene E Janes



Included in

Life Sciences Commons