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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 #381327

Research Project: Mitigation Approaches for Foodborne Pathogens in Cattle and Swine for Use During Production and Processing

Location: Meat Safety and Quality

Title: Assessing Shiga toxin-producing Escherichia coli in FSIS regulatory pork samples

item Bosilevac, Joseph - Mick
item SCOTT, MARIA - Food Safety Inspection Service (FSIS)
item TANKSON, JEANETTA - Food Safety Inspection Service (FSIS)

Submitted to: Journal of Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2021
Publication Date: 7/18/2021
Citation: Bosilevac, J.M., Scott, M., Tankson, J. 2021. Assessing Shiga toxin-producing Escherichia coli in FSIS regulatory pork samples [Abstract]. Journal of Food Protection. 84(Suppl A):56.

Interpretive Summary:

Technical Abstract: Introduction: Shiga toxin-producing E. coli (STEC) are associated with severe disease and recalls of contaminated beef but their presence in pork products has not been routinely investigated. Previously, 99% of screen positive pork samples could not be confirmed by culture isolation. Purpose: Resolve the discrepancies between molecular screening and culture isolation of regulated STEC in pork samples. Methods: Regulatory pork samples (n=1,102) were shipped from USDA FSIS to USDA ARS for analysis. Each broth was screened for STEC using the Bio-Rad VirX and SerO test kits. All broths positive for Shiga toxin (stx) and intimin (eae) genes were taken forward for culture isolation by direct plating to modified Rainbow, ChromSTEC, and washed sheeps blood agar. Additionally, samples determined to have regulated STEC serogroup(s) present (O26, O45, O103, O111, O121, O145, and O157) were immunomagnetically concentrated and plated to the same agars. Suspect colonies were selected and examined for stx, eae, and serogroup. Results: Of the 1,102 samples, 229 (20.8%) screened positive for the presence of stx and eae. Most of these (211) also screened positive for the presence of one or more of the regulated serogroup genes. Culture isolation yielded E. coli possessing at least one of the targeted genes (stx, eae, serogroup) from 164 samples, while 65 yielded no isolate. The source of the stx gene was confirmed in 38 samples while the source of the eae gene was confirmed in 115 samples. This included 3 samples containing a potential enterohemorrhagic E. coli (stx+ eae+), 2 being of regulated serogroups, and 24 samples containing multiple E. coli, each only possessing either stx or eae. Significance: While many pork samples screened positive for regulated STEC, most appear to be the result of mixed non-pathogen/severe pathogen contaminants rather than potential enterohemorrhagic E. coli of less common serogroups.