Applying phylogenomics to understand the emergence of Shiga Toxin producing Escherichia coli O157:H7 strains causing severe human disease in the United Kingdom

Timothy J. Dallman (Lead Author), Philip M. Ashton, Lisa Byrne, Neil T. Perry, Liljana Petrovska, Richard Ellis, Lesley Allison, Mary Hanson, Anne Holmes, George G. Gunn, Margo E. Chase-Topping, Mark E.J. Woolhouse, Kathie A. Grant, David L. Gally, John Wain, Claire Jenkins

Research output: Contribution to journalArticle

11 Downloads (Pure)

Abstract

Shiga Toxin producing Escherichia coli (STEC) O157:H7 is a recently emerged zoonotic pathogen with considerable morbidity. Since the serotype emerged in the 1980s, research has focussed on unravelling the evolutionary events from the E. coli O55:H7 ancestor to the contemporaneous globally dispersed strains. In this study the genomes of over 1000 isolates from human clinical cases and cattle, spanning the history of STEC O157:H7 in the United Kingdom were sequenced. Phylogenetic analysis reveals the ancestry, key acquisition events and global context of the strains. Dated phylogenies estimate the time to the most recent common ancestor of the current circulating global clone to 175 years ago, followed by rapid diversification. We show the acquisition of specific virulence determinates occurred relatively recently and coincides with its recent detection in the human population. Using clinical outcome data from 493 cases of STEC O157:H7 we assess the relative risk of severe disease including HUS from each of the defined clades in the population and show the dramatic effect Shiga toxin complement has on virulence. We describe two strain replacement events that have occurred in the cattle population in the UK over the last 30 years; one resulting in a highly virulent strain that has accounted for the majority of clinical cases in the UK over the last decade. This work highlights the need to understand the selection pressures maintaining Shiga-toxin encoding bacteriophages in the ruminant reservoir and the study affirms the requirement for close surveillance of this pathogen in both ruminant and human populations.
Original languageEnglish
Pages (from-to)13
JournalMicrobial Genomics
Volume1
Issue number3
Early online date14 Sep 2015
DOIs
Publication statusPublished - Sep 2015

Cite this