Location: Meat Safety and QualityTitle: High prevalence of extremely heat-resistant Escherichia coli in finished beef products
Submitted to: Journal of Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2020
Publication Date: 8/2/2020
Citation: Guragain, M., Schmidt, J., Bosilevac, J.M. 2020. High prevalence of extremely heat-resistant Escherichia coli in finished beef products. [Abstract] International Association for Food Protection Proceedings, August 2-5, 2020, San Antonio, Texas [Virtual]. Journal of Food Protection. 83(Supplement A):P2-99.
Technical Abstract: Introduction: Thermal processing is commonly used to reduce pathogens and spoilage bacteria in foods, including beef. Extremely heat resistant (XHR) E. coli possess a molecular determinant, the Locus of Heat Resistance (LHR), that allows them to survive processing treatments and potentially contaminate finished products. In recent separate studies the prevalence of XHR E. coli appeared higher in finished meat products compared to meat animals. Purpose: Determine the prevalence of XHR E. coli through the beef production continuum. Methods: For three lots of fed beef cattle, up to 12 generic E. coli (232 total) were isolated from each of the following: feces and hides at feedlot, feces and hides at abattoir, pre-evisceration carcasses, final carcasses, and strip loins (2 lots only). Isolates retaining viability following exposure to 60°C for 20min were judged XHR. LHR presence was determined using a multiplex-PCR that targeted the 5’-, 3’-, and two internal regions of the locus. Prevalences were compared using Fisher’s exact test. Results: Overall, 12.5% of isolates were XHR, represented by 3% of feedlot hide, 46% of final carcass and 62.5% of strip loin isolates. Eleven percent of isolates contained a full or partial LHR. LHR containing isolates were found amongst those from abattoir hides (3%), pre-evisceration carcasses (11%), final carcasses (7%), and strip loins (79%). In both cases, only isolates from strip loin were statistically different (P<0.05) compared to isolates from all other sources, which were not different (P>0.05) from one another. Fifty-nine percent of the XHR isolates possessed the LHR, while 65% of the LHR containing isolates showed the XHR phenotype. Significance: This study demonstrates that the occurrences of XHR and LHR+ E. coli increase as beef processing progresses. Further studies are required to identify the sources of XHR and/or LHR+ E. coli contaminating final products.