Shiga-like toxin-producing Escherichia coli O111 and associated hemolytic-uremic syndrome: a family outbreak.

To describe a family cluster of Shiga toxin-producing Escherichia coli O111ac:NM infection. The index case was identified as part of a United States prospective study of hemolytic-uremic syndrome. Epidemiologic investigation was conducted through interviews. E. coli O111:NM infection was characterized through culture and serology. Shiga toxin 1 and 2 gene sequences were determined with oligonucleotide DNA probes. All three children and both parents had nonbloody diarrhea, vomiting and abdominal cramps, and one child developed hemolytic-uremic syndrome. Shiga toxin 1- and 2-producing E. coli O111ac:NM was isolated from two children. IgG antibodies to E. coli O111 were detected in all three children. To our knowledge this is the first reported cluster of O111 infection and only the second caused by non-O157 Shiga toxin-producing E. coli in North America.