Hemolytic-uremic syndrome (HUS), first described in 1955, is a heterogeneous syndrome characterized by a triad of microangiopathic hemolytic anemia, acute renal failure, and thrombocytopenia. Initially thought to be a sporadic process, it is now recognized as the most common cause of acute renal failure in children.
In D+ HUS, with Shiga toxin-producing E. coli O157:H7 infection, the toxin binds, invades, and causes destruction of colonic epithelial cells, resulting in bloody diarrhea. Presumably because of the inflamed colon allowing transmural absorption, the toxin then enters the blood circulation. There the toxin binds to a glycolipid receptor known as globotriaosylceramide (Gb3), which results in endocytosis of the toxin usually within renal glomerular endothelial cells, and at times, other target organs. The expression of Gb3 receptors appears to be higher in infants and young children, which may in part explain the age-related propensity for developing HUS. Older children and adults have lower numbers of these receptors but may develop HUS whenever the combined effect of lipopolysaccharide and cytokines upregulate the expression of these Gb3 receptors.
With STEC infection, the incubation period is typically 3 to 4 days after exposure (range, 1 to 14 days).
Initial signs of symptomatic infection are vomiting, diarrhea, and significant abdominal pain. The diarrhea is often watery like typical viral gastroenteritis
Primary reflux is a congenital abnormality of the normally oblique insertion of the ureter through the bladder wall at the ureterovesical junction and is not associated with urinary tract or other congenital anomalies. Primary VUR usually resolves spontaneously during the first decade. Although the likelihood of resolution exceeds 80% when the VUR is mild, discovered in the first year of life, and unilateral, even the most severe reflux has a 40 to 50% spontaneous resolution rate. Patients with primary reflux rarely develop significant clinical sequelae such as proteinuria, hypertension, or renal insufficiency.