Location: Meat Safety and QualityTitle: Extremely heat-resistant Escherichia coli among cattle and beef
Submitted to: Journal of Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2018
Publication Date: 7/1/2018
Citation: Bosilevac, J.M. 2018. Extremely heat-resistant Escherichia coli among cattle and beef. Journal of Food Protection. 81 (Supplement A):P3-13.
Technical Abstract: Introduction: Extremely heat-resistant (XHR) Escherichia coli survive exposure of 60°C (140°F) for 60 min and in cooked (71°C, 160°F) ground beef patties. Whole genome sequencing of XHR E . coli identified a 14-kb genetic locus of heat resistance (LHR) that imparts the XHR phenotype. The prevalence of these E . coli among cattle and beef is unknown. Purpose: Establish the prevalence of XHR E. coli among cattle at harvest and determine if E. coli previously isolated from beef are XHR. Methods: A multiplex PCR assay was developed to detect the intact LHR in feces collected from fed (n=538), cull dairy (n=425), and cull beef (n=475) cattle arriving at nine beef-processing plants across the United States. Bacteria from the feces samples were heat-treated (80°C, 20 min) to isolate XHR E. coli. Archived E. coli O157:H7 (n=81), non-O157 adulterant Shiga toxin-producing E. coli (STEC; n=50), other STEC (n=97), and other E. coli (n=232) isolated from beef were screened for the LHR and XHR phenotype. Results: The intact LHR appeared present in 28.6, 14.4, and 11.4%, and absent from 24.7, 36.2, and 62.7% of fed, cull dairy, and cull beef cattle feces samples, respectively. The remainder of samples contained incomplete LHRs . The multiplex PCR cannot distinguish E. coli containing an intact LHR from mixtures of E. coli possessing non-intact LHRs. This is likely why only 10 strains with an intact LHR were isolated from the 1,151 feces samples. The intact LHR was found in 2.4% of the E. coli isolated from beef. None were recognized pathogens; however, one E. coli O157:H7 and one adulterant STEC-O103 contained an incomplete LHR. Significance: Portions of the LHR appear widespread, but few XHR E. coli with an intact LHR can be isolated from cattle and no pathogenic E. coli from beef have been found to possess an intact LHR.