Mitigation of biofilm production by Shiga toxin-producing Escherichia coli on manufacturing equipment surfaces using detergents and sanitizers
Parks, Amy R. H.
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Shiga toxin-producing Escherichia coli (STEC) are pathogens of concern for several commodities within the food industry and have been linked to a wide variety of recalls and outbreaks. In June 2012, six STEC serogroups (E. coli O26, O45, O103, O111, O121, and O145) joined E. coli O157:H7 on the list of adulterants in non-intact beef products, including ground beef, per the United States Department of Agriculture (USDA) Food Safety and Inspection Service (FSIS). Prior to these regulations, minimal research had been conducted on the non-O157 STEC serogroups identified above. Biofilms within a food processing environment can lead to cross-contamination or post-processing contamination of products, and can contain both non-pathogenic and pathogenic strains of microorganisms. Previous research has shown a select group of these organisms are able to attach and form biofilms on processing equipment surfaces and have shown increased resistance to commonly used sanitizers, such as quaternary ammonium and chlorine. Non-O157 STECs continue to gain importance as pathogens of concern, and it is important to understand how these organisms travel through the food supply chain from pre-harvest through consumer consumption. As such, more research is needed to understand how these organisms attach to food processing surfaces and form biofilms, as well as evaluate current cleaning and sanitation programs to ensure adequate removal of these bacteria and their biofilms. To meet those goals, a three-phase study was developed. The aim of phase 1 was to identify through colorimetric assay, if a variety of individual strains from each serogroup could attach to stainless steel and polystyrene at 25°C in minimal or full nutrient conditions. Phase 2 objectives were to enumerate attachment and subsequent biomass formation of STEC strains on stainless steel and polyurethane in minimal and full nutrient media at 25°C up to 48 h. Lastly, the objective of phase 3 was to determine the efficacy of a detergent and quaternary ammonium sanitizer combination against high attaching strains of non-O157 STEC serogroups. Overall, the findings of the study show that STECs have the ability to attach and form biomasses on equipment surfaces, including stainless steel and polyurethane. The results indicate that attachment and biomass formation of E. coli O26, O45, O111, O103, O121, O145, and O157:H7 are highly strain-dependent, and can be affected by environment conditions, such as availability of nutrients. Additionally, a robust cleaning and sanitation program that includes detergent and sanitizer, is the most effective at reducing the amount of attached bacteria from common food processing equipment surfaces like stainless steel. Understanding how these serogroups interact is essential in creating effective cleaning and sanitation programs to prevent and eliminate these bacteria within food production facilities.