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Shiga toxin (Stx) subtyping suggests that the clinical outcome of infections caused by Shiga toxin-producing ESCHERICHIA COLI (STEC) depends, in large part, on the STX genotype of the infecting strain. Whereas the presence of the STX2 or STX2C genotype is associated with the ability of STEC to cause the hemolytic uremic syndrome (HUS), strains possessing STX2D or STX2E have been isolated from patients with less severe disease. In addition to the type of Stx, the level of Stx production might be critical for the pathogenicity of STEC. Control of Stx expression appears to be at the level of transcription. Injury to microvascular endothelial cells is the key event underlying the pathogenesis of HUS. We could show that in addition to Stx, STEC also produces other putative virulence factors, such as cytolethal distending toxin, which can contribute to the endothelial injury by interference with the cell cycle, which results in inhibition of cell proliferation and finally cell death.

We report a patient with continuously recurring hemolytic-uremic syndrome due to factor H deficiency. First at the age of 3 months he showed signs of hemolytic anemia, thrombocytopenia and renal insufficiency, often recurring concomitantly with respiratory tract infections, despite weekly to twice weekly plasma substitution (20 ml/kg body weight). Now at the age of 3.5 years glomerular filtration rate is approximately 50 ml/min/1.73 m(2) and psychomotoric development is normal. Since factor H is mainly synthesized in the liver, hepatic transplantation has been proposed as curative treatment. Before justification of liver transplantation as the ultimate treatment for these patients, an international registry should be developed to optimize and standardize therapeutic alternatives.

Hemolytic-uremic syndrome (HUS) is mainly associated with foodborne infections by Shiga toxin-producing Escherichia coli (STEC). From January 1997 through December 2000, 394 children with HUS were evaluated in a prospective multicenter surveillance study in Germany and Austria (incidences, 0.7/100,000 and 0.4/100,000 children <15 years old, respectively). Blood leukocytosis was associated with increased detection of STEC in stool cultures (P<.01) and a more severe disease course. Risk of death was associated with cerebral involvement (P<.01). Most strikingly, non-O157:H7 STEC were detected in 43% of stool cultures of patients with HUS: O26 was detected in 15%, sorbitol-fermenting O157:H(-) in 10%, O145 in 9%, O103 in 3%, and O111 in 43%. Patients with O157:H7 serotypes required dialysis for a longer time and had bloody diarrhea detected more frequently, compared with patients with non-O157:H7 serotypes (P<.05). This large study in children with HUS underlines the rising importance of non-O157:H7 serotypes, and, despite increased public awareness, the number of patients remained unchanged.