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Blended virulence profiles of E. coli 0104:H4 explain progression in Germany outbreak

Bielaszewska M. Lancet Infect Dis. 2011;doi:10.1016/S1473-3099(11)70165-7.

Researchers from Germany said the blended virulence profile of the rare Escherichia coli 0104:H4 strain is what led to the high progression of 810 hemolytic uremic syndrome cases and 39 deaths that have occurred in Germany since the beginning of May, according to new findings published in The Lancet Infectious Diseases.

“This outbreak demonstrates that blended virulence profiles in enteric pathogens, introduced into susceptible populations, can have extreme consequences for infected people,” the researchers wrote. “This pathogen, and this outbreak, will have profound implications for disease detection, reporting, food safety, and our understanding of microbial pathogenesis.”

Martina Bielaszewska, MD, and colleagues assessed stool samples of 80 patients submitted to the National Consulting Laboratory for Hemolytic Uremic Syndrome in Münster, Germany, between May 23 and June 2. Polymerase chain reaction (PCR) was used to assess virulence genes of Shiga toxin-producing E. coli; a new multiplex PCR was used to assess characteristic features of the outbreak strain.

All isolates were of the HUSEC041 clone, according to the researchers. All shared virulence profiles combined Shiga-toxin-producing E. coli and enteroaggregative E. coli loci and expressed phenotypes that define Shiga toxin-producing E. coli and enteroaggregative E. coli, including production of Shiga toxing 2 and aggregative adherence to epithelial cells.

Moreover, isolates were susceptible to carbapenems, but resistant to all cephalosporins and penicillins.

In an accompanying editorial, Hugh Pennington, MBBS, PhD, emeritus professor of bacteriology at the University of Aberdeen, Scotland, wrote: “In this large outbreak in Germany, most cases of the syndrome have been in young and middle-age adults, particularly women. Two factors probably explain this scenario: the patterns of consumption of the vector and an increased likelihood of developing hemolytic uremic syndrome because of the high virulence of the clone.”

Disclosure: The study was funded by the German Federal Ministry of Education and Research Network Zoonoses.

The May and June outbreak of E. coli diarrhea in Germany is of great interest for a number of reasons. The rate of hemolytic uremic syndrome (HUS) seen is more than double the rate seen in Shiga toxin-producing E. coli (STEC) infections in the US with most cases in Germany occurring in adults while most cases in the US have been seen in children. The different disease seen with the German outbreak relates to the unique pathogen. E. coli O104:H4 is a combination of two well known pathogens, STEC and enteroaggregative E. coli. We don't know if this 'Super E. coli' strain will die out like SARS coronavirus or will be a major threat to world public health.

Herbert L. DuPont, MD
St. Luke's Episcopal Hospital

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