Skip to main content
ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Meat Safety and Quality » Research » Publications at this Location » Publication #412293
Research Project: Holistic Tactics to Advance the Microbiological Safety and Quality of the Red Meat Continuum

Location: Meat Safety and Quality

Title: Pathogenomes of Shiga toxin positive and negative Escherichia coli O157:H7 strains TT12A and B: comprehensive phylogenomic analysis using closed genomes

Author
item KALALAH, ANWAR - University Of Texas At San Antonio
item KOENIG, SARA - University Of Texas At San Antonio
item FENG, PETER - Food And Drug Administration(FDA)
item Bosilevac, Joseph - Mick
item Bono, James - Jim
item EPPINGER, MARK - University Of Texas At San Antonio

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/1/2024
Publication Date: 2/29/2024
Citation: Kalalah, A.A., Koenig, S.S., Feng, P.C., Bosilevac, J.M., Bono, J.L., Eppinger, M. 2024. Pathogenomes of Shiga toxin positive and negative Escherichia coli O157:H7 strains TT12A and B: comprehensive phylogenomic analysis using closed genomes [abstract]. American Society for Microbiology. No. 5741.

Interpretive Summary:

Technical Abstract: Background: Shiga toxin-producing Escherichia coli are globally disseminated zoonotic pathogens that cause life-threatening food-borne disease in humans. Among these, the enterohemorrhagic serotype O157:H7 evolved from an enteropathogenic O55:H7 ancestor through the recurrent toxigenic conversion by Shiga toxin-converting bacteriophages. However, atypical strains that lack Shiga toxin, the characteristic virulence hallmark, are circulating in this lineage. Methods: For this study, we sequenced and analyzed the pathogenome make-up and virulence inventories of stx+ and stx- strains TT12A and TT12B isolated from a patient presenting with hemorrhagic colitis. Sequencing the genomes to closure proved critical to catalogue subtle strain differentiating sequence and structural polymorphisms at a high-level of phylogenetic accuracy and resolution. We determined the strains’ phylogenomic position within the O157:H7 lineage and genomic basis of the atypical non-shigatoxigenic status. Results: Phylogenomic profiling of the core genomes revealed indifferent SNP- and MLST profiles of TT12A and B similar to near clonal outbreak isolates. The strains’ Stx and non- Stx prophage inventories, however, are notably different. The attenuated status of TT12B is explained by the absence of both Stx1a and Stx2a prophages carried by TT12A, and the strains also feature alteration in their strain-specific and shared non-Stx prophage complement. Conclusion: Phenotypic characterization indicated that culture growth of TT12A and B is directly impacted by the strains’ distinct lytic phage complement upon prophage mobilization. Altogether, our phylogenomic and phenotypic analyses show that these isogenic strains are intimately related yet are on divergent evolutionary paths.