Methods for screening and isolating extremely heat resistant Escherichia coli from meat sources

Authors: Guragain, Manita; Smith, Gregory - Greg; Bosilevac, Joseph - Mick

Submitted to: Life
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/2024
Publication Date: 9/5/2024
Citation: Guragain, M., Smith, G.E., Bosilevac, J.M. 2024. Methods for screening and isolating extremely heat resistant Escherichia coli from meat sources. Life. 14:1123. https://doi.org/10.3390/life14091123.
DOI: https://doi.org/10.3390/life14091123

Interpretive Summary: Consumption of meat and produce contaminated with pathogenic E. coli from animal sources is associated with human illnesses and outbreaks. Food industries rely on antimicrobial interventions to control pathogenic and spoilage microbes in the final product. Heat treatment is one of the commonly used interventions in meat processing. Extreme heat resistant E. coli can survive the meat processing and cooking temperature. Therefore, detection of extreme heat resistant E. coli is important to devise effective control strategies against pathogens and spoilage organisms. Here, we describe the rapid and reliable methods to screen for extreme heat resistant E. coli in meat.

Technical Abstract: Meat animals harbor diverse E. coli populations in their digestive tract and can serve as a source of pathogenic E. coli. Consumption of meat and produce contaminated with virulent E. coli from animal sources is associated with human illnesses and outbreaks. Heat treatment is one of the commonly used antimicrobial interventions during meat processing to ensure effective reduction in microbial load. Extreme heat resistance (XHR) has been reported among meat borne E. coli, and is mainly attributed to an ~ 15-19 kb genetic element known as the transmissible locus of stress tolerance (tLST). The XHR E. coli can resist treatments used during meat processing and cooking. Therefore, detection of heat resistant E. coli is important to devise effective control measures to prevent meat spoilage and ensure meat safety. We present here methods used to 1) screen for tLST genes by multiplex PCR; and 2) screen and isolate XHR E. coli from meat sources. The mode of heat exposure affects the outcome of XHR testing hence the protocols were optimized to achieve maximum agreement between tLST genotype and XHR phenotype.