Escherichia coli O104:H4 str. C227-11 Genome sequencing and assembly

A large outbreak of diarrhea caused by a Shiga toxin-producing Escherichia coli belonging to an unusual serotype (O104:H4) began in Germany in May 2011. Of the more than 2750 persons infected, ~25% developed hemolytic uremic syndrome (HUS), indicating that this strain is notably more virulent than enterohemorrhagic E coli (EHEC), the most common Shiga toxin producing agent of diarrhea and HUS. Preliminary genetic characterization of the outbreak strain suggested that it was not a typical EHEC strain but is instead more similar to a distinct E. coli pathotype, enteroaggregative E. coli (EAEC). We used third-generation single-molecule real-time DNA sequencing to determine the complete genome sequence of the German outbreak strain as well as the genome sequences of seven diarrhea-associated EAEC serotype O104:H4 strains from Africa and 4 EAEC reference strains belonging to distinct serotypes. To ascertain the likely evolutionary origins of the new outbreak strain, genome-wide comparisons were performed using these EAEC genomes as well as those of 4 previously sequenced E. coli isolates.