Characteristics of pAA-positive and pAA-negative EHEC O104:H4 isolatesa and clinical outcomes of infection in the respective patients.

aThe identity of all isolates as EHEC O104:H4 outbreak strain was confirmed using the multiplex real-time PCR targeting rfbO104, fliCH4, and stx2a[24] and multilocus sequence typing, which demonstrated that all belong to ST678 typical for the outbreak strain [8].bHUS, hemolytic uremic syndrome; BD, bloody diarrhea; D, diarrhea without visible blood.c1, initial isolate; 2, follow-up isolate; the number in parenthesis indicates the time interval between recovery of the initial and the follow-up isolate.d+/+, PCR amplicon of corresponding size and hybridization signal on the 75-kb plasmid present; −/−, no PCR amplicon, no hybridization signal present.eSizes of plasmids in kilobase pairs (kb).fStx2a titers were defined as the highest dilutions of sterile culture filtrates that caused cytotoxicity in 50% Vero cells after 72 h.gAA, aggregative adherence pattern (HCT-8 cells).