Highly Pathogenic Clone of Shiga Toxin–ProducingEscherichia coliO157:H7, England and Wales

• DOI: 10.3201/eid2412.180409
• Publication Date: 2018-11-05T15:58:43Z
• Authors: Lisa Byrne; Timothy J. Dallman; Natalie Adams; Amy F.W. Mikhail; Noel McCarthy; Claire Jenkins
• Keywords: clone (Java method); Multilocus sequence typing

We used whole-genome sequencing to investigate the evolutionary context of an emerging highly pathogenic strain Shiga toxin-producing Escherichia coli (STEC) O157:H7 in England and Wales. A timed phylogeny sublineage IIb revealed that clone evolved from a STEC stx-negative ancestor ≈10 years ago after acquisition bacteriophage encoding toxin (stx) 2a, which turn had stx2c progenitor ≈20 ago. Infection with stx2a was significant risk factor for bloody diarrhea (OR 4.61, 95% CI 2.24-9.48; p<0.001), compared infection other strains within IIb. Clinical symptoms cases infected clones were comparable, despite loss stx2c. Our analysis highlighted dynamic nature Stx-encoding bacteriophages history IIb, not previously associated severe clinical symptoms.