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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Meat Safety and Quality » Research » Publications at this Location » Publication #305671
Title: Biofilm formation and sanitizer resistance of Escherichia coli 0157:H7 strains isolated from "High Event Period" meat contamination

Author
item Wang, Rong
item Kalchayanand, Norasak - Nor
item King, David - Andy
item Luedtke, Brandon
item Bosilevac, Joseph - Mick
item Arthur, Terrance

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/6/2014
Publication Date: 11/1/2014
Publication URL: http://handle.nal.usda.gov/10113/60063
Citation: Wang, R., Kalchayanand, N., King, D.A., Luedtke, B.E., Bosilevac, J.M., Arthur, T.M. 2014. Biofilm formation and sanitizer resistance of Escherichia coli 0157:H7 strains isolated from "High Event Period" meat contamination. Journal of Food Protection. 77(11):1982-1987.

Interpretive Summary: E. coli O157:H7 can cause serious foodborne illness outbreaks. In the meat industry, a “High Event Period” (HEP) is defined as a time period during which commercial meat plants experience a higher than usual rate of E. coli O157:H7 contamination. Our previous genetic analysis indicated that within each HEP, contamination in raw beef products were caused by a singular dominant O157 strain type, suggesting that HEP contamination might occur after carcasses exit the kill floor instead of originating from animal hide. This was in disagreement with the current beef contamination model stating that contamination occurs when incoming pathogen load on animal hides, which consists of diverse strain types of E. coli 0157:H7, exceed the intervention capacity. Thus, we hypothesize that the HEPs may be due to certain in-plant colonized E. coli O157:H7 strains that are better able to survive sanitization through biofilm formation (bacterial attachment and colonization on solid surfaces). Our data showed that the HEP strains demonstrated significantly higher ability of biofilm formation compared to the control strains. Biofilms by the HEP strains also exhibited significantly stronger resistance to common sanitizers, including Vanquish TM, ProOxine TM, and chlorine. These results indicated that biofilm formation and sanitization resistance may contribute to HEP beef contamination by E. coli O157:H7, which highlights the importance of proper and complete sanitization of food contact surfaces and food processing equipments in commercial meat plants.

Technical Abstract: In the meat industry, a “High Event Period” (HEP) is defined as a time period during which commercial meat plants experience a higher than usual rate of E. coli O157:H7 contamination. Genetic analysis indicated that within a HEP, most of the E. coli O157:H7 strains belong to a singular dominant strain type. This was in disagreement with the current beef contamination model stating that contamination occurs when incoming pathogen load on animal hides, which consists of diverse strain types of E. coli 0157:H7, exceed the intervention capacity. Thus, we hypothesize that the HEP contamination may be due to certain in-plant colonized E. coli O157:H7 strains that are better able to survive sanitization through biofilm formation. To test our hypothesis, a collection of 45 E. coli O157:H7 strains isolated from HEP beef contamination incidents and a panel of 47 E. coli O157:H7 strains of diverse genetic backgrounds were compared for biofilm formation and sanitizer resistance. Biofilm formation was tested on 96-well polystyrene plates for 1 – 6 days. Biofilm cell survival and recovery growth after sanitization were compared between the two strain collections using common sanitizers, including quaternary ammonium chloride (QAC), chlorine, and sodium chlorite. No difference in “early stage” biofilms was observed between the two strain collections after incubation at 22 – 25oC for 1 or 2 days. However, the HEP strains demonstrated significantly higher potency of “mature” biofilm formation after incubation for 4 – 6 days. Biofilms of the HEP strains also exhibited significantly stronger resistance to sanitization. These data suggest that biofilm formation and sanitization resistance could play a role in HEP beef contamination by E. coli O157:H7, which highlights the importance of proper and complete sanitization of food contact surfaces and food processing equipments in commercial meat plants.