Whole Genome Sequencing of an Unusual Serotype of Shiga Toxin–producingEscherichia coli

Tim Dallman,Chloe Bishop,Kathie A Grant,Neil Perry,Claire Jenkins,Lisa Cross,Bente Olesen

doi:10.3201/eid1908.130016

Abstract

Shiga toxin–producing Escherichia coli serotype O117:K1:H7 is a cause of persistent diarrhea in travelers to tropical locations. Whole genome sequencing identified genetic mechanisms involved in the pathoadaptive phenotype. Sequencing also identified toxin and putative adherence genes flanked by sequences indicating horizontal gene transfer from Shigella dysenteriae and Salmonella spp., respectively.

Highlights

Shiga toxin–producing Escherichia coli serotype O117:K1:H7 is a cause of persistent diarrhea in travelers to tropical locations
There are >400 serotypes of Shiga toxin–producing Escherichia coli (STEC), and >100 of these are known to be associated with severe disease in humans (1)
Those serotypes associated with more severe disease generally harbor additional virulence genes, such as eae, which is encoded on the locus of enterocyte effacement, or virulence regulation genes, such as aggR, which is located on the aggregative adherence plasmid

Summary

Introduction

Shiga toxin–producing Escherichia coli serotype O117:K1:H7 is a cause of persistent diarrhea in travelers to tropical locations. STEC are defined by the presence of 1 or both phage-encoded Shiga toxin genes stx[1] and stx[2] Those serotypes associated with more severe disease generally harbor additional virulence genes, such as eae (intimin), which is encoded on the locus of enterocyte effacement, or virulence regulation genes, such as aggR, which is located on the aggregative adherence plasmid. Both of these genes mediate attachment of the bacteria to the host gut mucosa (2). DOI: http://dx.doi.org/eid1908.130016 because it was negative for the production of lysine decarboxylase and b-galactosidase (ortho-nitrophenol test) and positive only for stx[1]

Objectives

Conclusion