Distribution of extremely heat-resistant Escherichia coli in the beef production and processing continuum.

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...