Harnessing diverse prophages of STEC O157:H7 phage-type 8 for rapid identification of fresh produce-associated STEC strains

JYN Nale, SC Tongue, NH Holden

Research output: Contribution to conferencePaper


The Shigatoxigenic Escherichia coli (STEC) serotype O157:H7 is a priority foodborne pathogen in humans. STEC strains in the same serotype can be classified according to their susceptibility to lysis by a set of bacterial lytic viruses, bacteriophages, termed phage typing. In many parts of the world the majority of STEC outbreaks are now derived from plant-based food, with an apparent association of phage-type (PT) 8 strains. Thus, rapid and reproducible identification system to supplement existing methods is needed for these strains. Here, we took a sequence-based approach to identify specific molecular markers. We identified twenty-five prophages (genome-embedded phages) in a representative STEC O157:H7 serotype, isolate 644-PT8, from lettuce. Seven molecular markers unique to 644-PT8 prophage genes were designed to enable rapid and accurate identification of PT8 strains. These markers had the added benefit of discriminating STEC based on their phage repertoire, allowing for detection STEC strains from additional sources. The markers comprised of primers sets that each produced a unique single amplicon of varying sizes (169, 306, 507, 798,1022, 1855, 2371 bp) from the bacterial host genome, 644-PT8, for a multiplex PCR. The markers showed 100% specificity for E. coli O157:H7 in public databases and clustered other serotype strains into specific clades, using the BLASTn tool. These molecular markers provide a valuable novel diagnostic tool for the identification of isolates in different niches that could enhance STEC surveillance. Future work will focus on creating an easy-to-use pipeline for STEC identification in silico, and test feasibility of adoption from field isolates.
Original languageEnglish
Publication statusPrint publication - 15 Jun 2023
Event13th International Gut Microbiology Symposium 2023 - P&J LIVE, ABERDEEN, United Kingdom
Duration: 13 Jun 202315 Jun 2023


Conference13th International Gut Microbiology Symposium 2023
Country/TerritoryUnited Kingdom
Internet address


  • Shigatoxigenic Escherichia coli
  • O157:H7
  • Molecular markers
  • phage-type
  • Diagnostic biomarkers


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