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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 #390840
Research Project: Holistic Tactics to Advance the Microbiological Safety and Quality of the Red Meat Continuum

Location: Meat Safety and Quality

Title: Development and validation of high-resolution melting assays for the detection of potentially virulent strains of Escherichia coli O103 and O121

Author
item VELEZ, FRANK - Florida State University
item Bosilevac, Joseph - Mick
item DELANNOY, SABINE - French Agency For Food, Environmental And Occupational Health & Safety (ANSES)
item FACH, PATRICK - French Agency For Food, Environmental And Occupational Health & Safety (ANSES)
item NAGPAL, RAVINDER - Florida State University
item SINGH, PRASHANT - Florida State University

Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/7/2022
Publication Date: 9/1/2022
Citation: Velez, F.J., Bosilevac, J.M., Delannoy, S., Fach, P., Nagpal, R., Singh, P. 2022. Development and validation of high-resolution melting assays for the detection of potentially virulent strains of Escherichia coli O103 and O121. Food Control. 139. Article 109095. https://doi.org/10.1016/j.foodcont.2022.109095.
DOI: https://doi.org/10.1016/j.foodcont.2022.109095

Interpretive Summary: Sensitive and accurate tests are needed to detect Shiga toxin-producing Escherichia coli (STEC) contaminated meat because STEC are dangerous pathogens. O103 and O121 are two types of dangerous STEC, but there are safe non-illness causing E. coli of these types that produce false positive tests. Therefore, we designed and reported two new tests that can detect and distinguish the pathogenic STEC-O103 and STEC-O121 from the non-pathogen O103 and O121 E. coli. In this report the two tests were compared to the official method used by regulators on real-world samples collected from pork and beef. Results showed that these two tests more accurately identified samples containing pathogens than the official method.

Technical Abstract: Virulent strains of Shiga toxin-producing Escherichia coli (STEC) serogroups O103 and O121 are considered adulterants in beef. Two high-resolution melting (HRM)real-time PCR assays were standardized for the specific detection and discrimination of potentially virulent and avirulent strains of E. coli O103 and O121. The two standardized assays were extensively validated using 215 pure culture strains, laboratory inoculated food samples, and naturally contaminated beef (n = 84) and pork (n = 84) enrichments collected from the red meat surveillance program. Both HRM assays showed 100% inclusivity and exclusivity using pure culture strains and enriched spiked food samples. Data from this study shows the ability of the standardized assays to specifically detect the strains of each target serogroup and, most importantly, to differentiate the strains present into potentially virulent or avirulent groups. The assays standardized in this study can be helpful for food surveillance programs and help mitigate product loss due to the presence of avirulent strains lacking crucial virulence genes (stx and eae).