Byrne, L; Dallman, TJ; Adams, N; Mikhail, AFW; McCarthy, N; Jenkins, C (2018) Highly Pathogenic Clone of Shiga Toxin-Producing Escherichia coli O157:H7, England and Wales. Emerg. Inf. Dis. 24 2303-2308
Byrne, L; Dallman, TJ; Adams, N; Mikhail, AFW; McCarthy, N; Jenkins, C (2018) Highly Pathogenic Clone of Shiga Toxin-Producing Escherichia coli O157:H7, England and Wales. Emerging Infectious Diseases 24 2303-2308
We used whole-genome sequencing to investigate the evolutionary context of an emerging highly pathogenic strain of Shiga toxin–producing Escherichia coli (STEC) O157:H7 in England and Wales. A timed phylogeny of sublineage IIb revealed that the emerging clone evolved from a STEC O157:H7 stx-negative ancestor ≈10 years ago after acquisition of a bacteriophage encoding Shiga toxin (stx) 2a, which in turn had evolved from a stx2c progenitor ≈20 years ago. Infection with the stx2a clone was a significant risk factor for bloody diarrhea (OR 4.61, 95% CI 2.24–9.48; p<0.001), compared with infection with other strains within sublineage IIb. Clinical symptoms of cases infected with sublineage IIb stx2c and stx-negative clones were comparable, despite the loss of stx2c. Our analysis highlighted the highly dynamic nature of STEC O157:H7 Stx-encoding bacteriophages and revealed the evolutionary history of a highly pathogenic clone emerging within sublineage IIb, a sublineage not previously associated with severe clinical symptoms.