This might partly be due to the low number of HUS cases in our study, and it is noteworthy that the two O104:H4 HUS isolates were from Swedish patients that visited Germany during the O104:H4 outbreak in 2011, exhibiting same serotype, stx2a subtype and absence of eae with the outbreak strain, thus they might be the same strain. The gene discussed is STX2; the disease is hemolytic-uremic syndrome.