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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 #411054
Research Project: Identification, Genomic Characterization, and Metabolic Modeling of Foodborne Pathogens in the Meat Production Continuum

Location: Meat Safety and Quality

Title: Pathogenomes and virulence profiles of representative big six non-O157 serogroup Shiga toxin-producing Escherichia coli

Author
item KALALAH, ANWAR - University Of Texas At San Antonio
item KOENIG, SARA - University Of Texas
item Bono, James - Jim
item Bosilevac, Joseph - Mick
item EPPINGER, MARK - University Of Texas At San Antonio

Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/29/2024
Publication Date: 3/18/2024
Citation: Kalalah, A.A., Koenig, S.S.K., Bono, J.L., Bosilevac, J.M., Eppinger, M. 2024. Pathogenomes and virulence profiles of representative big six non-O157 serogroup Shiga toxin-producing Escherichia coli. Frontiers in Microbiology. 15. Article 1364026. https://doi.org/10.3389/fmicb.2024.1364026.
DOI: https://doi.org/10.3389/fmicb.2024.1364026

Interpretive Summary: Shiga toxin (Stx)-producing Escherichia coli (STEC) are responsible for global and widespread human food-borne disease. In the United States, STEC O157:H7 is the most common STEC responsible for human infections. The next six most common non-O157 STEC account for over half of the total STEC infections. The genomes of STEC O157:H7 isolates have been studied extensively while those of the next six non-O157 STEC have lagged. This study describes the complete closed genomes from a reference collection of non-O157 isolates. The availability of high-quality closed reference genomes for these six STEC along with their variability in Shiga toxin-production which relates to their ability to cause severe disease will provide a valuable reference for the scientific community to use as they gain further insights into the evolutionary trajectories of these important STEC serotypes.

Technical Abstract: Shiga toxin (Stx)-producing Escherichia coli (STEC) of non-O157:H7 serotypes are responsible for global and widespread human food-borne disease. Among these serogroups, O26, O45, O103, O111, O121, and O145 account for the majority of clinical infections and are colloquially referred to as the "Big Six." The "Big Six" strain panel we sequenced and analyzed in this study are reference type cultures comprised of six strains representing each of the non-O157 STEC serogroups curated and distributed by the American Type Culture Collection (ATCC) as a resource to the research community under panel number ATCC MP-9. The application of long- and short-read hybrid sequencing yielded closed chromosomes and a total of 14 plasmids of diverse functions. Through high-resolution comparative phylogenomics, we cataloged the shared and strain-specific virulence and resistance gene content and established the close relationship of serogroup O26 and O103 strains featuring flagellar H-type 11. Virulence phenotyping revealed statistically significant differences in the Stx-production capabilities that we found to be correlated to the strain's individual stx-status. Among the carried Stx1a, Stx2a, and Stx2d phages, the Stx2a phage is by far the most responsive upon RecA-mediated phage mobilization, and in consequence, stx2a + isolates produced the highest-level of toxin in this panel. The availability of high-quality closed genomes for this "Big Six" reference set, including carried plasmids, along with the recorded genomic virulence profiles and Stx-production phenotypes will provide a valuable foundation to further explore the plasticity in evolutionary trajectories in these emerging non-O157 STEC lineages, which are major culprits of human food-borne disease.