Distribution of Extremely Heat-Resistant Escherichia coli in the Beef Production and Processing Continuum

• Published in: Journal of food protection Vol. 86; no. 1; p. 100031
• Main Authors: Guragain, Manita, Schmidt, John W., Dickey, Aaron M., Bosilevac, Joseph M.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.01.2023; Elsevier
• Subjects: Animals; Antimicrobial interventions; Beef; Cattle; Escherichia coli; Hot Temperature; Locus of Heat Resistance (LHR); Meat; Transmissible locus of stress tolerance (tLST); Whole-genome sequencing; Locus of Heat Resistance (LHR); Antimicrobial interventions; Transmissible locus of stress tolerance (tLST); Beef; Cattle; Whole-genome sequencing
• ISSN: 0362-028X; 1944-9097
• DOI: 10.1016/j.jfp.2022.100031

•Extremely heat-resistant (XHR) E. coli were infrequent in early production stages.•The locus of heat resistance (LHR) provided XHR phenotype to 85% of the isolates.•LHR+E. coli were more frequent in postintervention and finished beef products.•Current beef processing interventions appear to control LHR+E. coli.•LHR+E. coli in final products may be introduced in late processing stages. Understanding the dynamics of stress-resistant Escherichia coli (E. coli) across the meat production and processing continuum is important for tracking sources of such microbes and devising effective modes of control. The Locus of Heat Resistance (LHR) is a ∼14–19 Kb genetic element imparting extreme heat resistance (XHR) in Enterobacteriaceae. It has been hypothesized that thermal and antimicrobial interventions applied during meat processing may select for LHR+E. coli. Thus, our goal was to study the prevalence and molecular biology of LHR+E. coli among lots of beef cattle (n = 3) from production through processing. Two hundred thirty-two generic E. coli isolated from the same animals through seven stages of the beef processing continuum (cattle in feedyards to packaged strip loins) were examined. LHR+E. coli were rare (0.6%; 1 of 180) among the early stages of the beef continuum (feces and hides at feedlot, feces and hides at harvest, and preevisceration carcasses), whereas the prevalence of LHR+E. coli on final carcasses and strip loins was remarkably higher. Half (14 of 28) of the final carcass E. coli possessed the LHR, while 79.2% (19 of 24) of the strip loin E. coli did. Eighty-five percent (29 of 34) of the LHR+E. coli presented with the XHR phenotype. The selection or enrichment of LHR+E. coli from harvest steps to the final products appeared unlikely as the LHR+E. coli isolates were effectively controlled by antimicrobial interventions typically used during beef processing. Further, whole-genome sequencing of the isolates suggested LHR+E. coli are persisting in the chilled processing environment and that horizontal LHR transfer among E. coli isolates may take place.