2011 E. coli outbreak has blended adherence-toxicity virulence profile
MedWire News: The Escherichia coli outbreak of May 2011 was caused by a O104:H4 strain with a blended virulence profile that combined Shiga toxin 2-production and adherence to intestinal epithelial cells, study results show.
All the isolates belonged to a clone (HUSEC041) which was first isolated in Germany from a patient with hemolytic uremic syndrome (HUS) in 2001.
"This pathogen, and this outbreak, will have profound implications for disease detection, reporting, food safety, and our understanding of microbial pathogenesis," Helge Karch (University of Münster, Germany) and colleagues comment in The Lancet.
From early May 2011, an outbreak of HUS and bloody diarrhea caused by E. coli O104:H4 spread throughout Germany and beyond. As of June 20 2011, 810 cases of HUS, 684 non-HUS cases, and 39 deaths have been reported.
"To gain insight into the apparently augmented virulence of the outbreak strain, we analyzed virulence profiles and relevant phenotypes of outbreak isolates recovered in our laboratory," Karch et al comment.
They analyzed stool samples from 80 patients and screened isolate cultures with standard polymerase chain reaction (PCR) for virulence genes of Shiga-toxin-producing E. coli and a newly developed multiplex PCR for characteristic features of the outbreak strain.
Virulence profiles of the isolates were determined with PCR targeting typical virulence genes of Shiga-toxin-producing E. coli and of other intestinal pathogenic E. coli.
All isolates had virulence profiles that combined those of two different enterovirulent E. coli - enterohemorrhagic E. coli and enteroaggregative E. coli, facilitating Shiga toxin 2-production and intestinal epithelial adherence, respectively.
The outbreak isolates, but not the 2001 strain, also had an extended spectrum ß-lactamase antibiotic resistance profile.
In an accompanying commentary, Hugh Pennington, of the University of Aberdeen in the UK, said the blending of virulence traits "could explain why so many - about 30% of those infected - in the German outbreak have developed HUS."
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By Andrew Czyzewski