Shiga Toxin 2 Overexpression in Escherichia Coli O157:H7 Strains Associated With Severe Human Disease

Microb Pathog. 2011 Dec;51(6):466-70. doi: 10.1016/j.micpath.2011.07.009. Epub 2011 Aug 16.

Abstract

Variation in disease severity among Escherichia coli O157:H7 infections may result from differential expression of Shiga toxin 2 (Stx2). Eleven strains belonging to four prominent phylogenetic clades, including clade 8 strains representative of the 2006 U.S. spinach outbreak, were examined for stx2 expression by real-time PCR and western blot analysis. Clade 8 strains were shown to overexpress stx2 basally, and following induction with ciprofloxacin when compared to strains from clades 1-3. Differences in stx2 expression generally correlated with Stx2 protein levels. Single-nucleotide polymorphisms identified in regions upstream of stx2AB in clade 8 strains were largely absent in non-clade 8 strains. This study concludes that stx2 overexpression is common to strains from clade 8 associated with hemolytic uremic syndrome, and describes SNPs which may affect stx2 expression and which could be useful in the genetic differentiation of highly-virulent strains.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Cluster Analysis
  • Disease Outbreaks*
  • Escherichia coli Infections / complications
  • Escherichia coli Infections / epidemiology
  • Escherichia coli Infections / microbiology*
  • Escherichia coli O157 / classification
  • Escherichia coli O157 / genetics
  • Escherichia coli O157 / isolation & purification
  • Escherichia coli O157 / pathogenicity*
  • Gene Expression*
  • Hemolytic-Uremic Syndrome / epidemiology
  • Hemolytic-Uremic Syndrome / microbiology*
  • Humans
  • Molecular Typing
  • Polymorphism, Single Nucleotide
  • Shiga Toxin 2 / biosynthesis*
  • Spinacia oleracea / microbiology
  • United States / epidemiology
  • Virulence

Substances

  • Shiga Toxin 2