Clinical manifestations and diagnosis of shiga-like toxin associated (typical) hemolytic uremic syndrome in children

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Clinical manifestations and diagnosis of Shiga-like toxin associated (typical) hemolytic uremic syndrome in children
Patrick Niaudet, MD
Section Editors
Tej K Mattoo, MD, DCH, FRCP
Sheldon L Kaplan, MD
Deputy Editor
Melanie S Kim, MD
Last literature review version 18.3: septiembre 2010 | This topic last updated: octubre 7, 2010 (More)
INTRODUCTION — The hemolytic uremic syndrome(HUS) is defined by the simultaneous occurrence of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal injury [1]. It is one of the main causes of acute renal injury in children under the age of three years.
This disorder is divided by whether or not there is an association with bacteria that produce a shiga-like toxin.
Shiga-like toxin associated HUS — Shiga-like toxin (Stx)associated HUS is the most common form of HUS in children accounting for 90 percent of all cases. It usually occurs after a prodromal episode of diarrhea that is frequently bloody. In the majority of cases, Stx HUS is associated with strains of Escherichia coli that produce a Shiga toxin [2-5]. This form is also referred to as typical, classical, or diarrhea-associated HUS, D+ HUS, or Shigatoxin-associated HUS. Cases of HUS in children due to Shiga toxin-producing E. coli infections other than colitis (eg, urinary tract infections) can occur [6,7]. Although these cases are not associated with diarrhea, the clinical course and pathophysiology are the same as the D+ HUS and will be included in the discussion on Stx HUS. In addition, D+ HUS associated with Shigella dysenteriae serotype 1 willbe included in the discussion of Stx HUS [8,9].

* Non-shiga toxin associated HUS — Non-shiga toxin (NStx) associated HUS is a heterogeneous group of disorders distinguished clinically by the absence of diarrhea or Shiga toxin-producing E. coli infection [10,11]. This disorder is also referred to as atypical, nondiarrhea-associated HUS, D- HUS, or sporadic HUS. Complement disorders involvingfactors H, I, and membrane cofactor protein and Streptococcus pneumoniae infection have been associated with cases of NStx HUS. The clinical manifestations, diagnosis, treatment, and prognosis of NStx HUS are presented separately. (See "Atypical hemolytic uremic syndrome in children".)
The clinical manifestations and diagnosis of Stx HUS in children are presented in this topic review. Thetreatment and prognosis of this disorder are presented separately. (See "Treatment of Shiga-like toxin associated (typical) hemolytic uremic syndrome in children".)
Stx HUS is also a different disorder from thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS) in adults. This is discussed in detail separately. (See "Causes of thrombotic thrombocytopenic purpura-hemolytic uremic syndromein adults".)
MICROBIOLOGY — Stx HUS in children occurs after an infection with Shiga toxin-producing enterohemorrhagic E. coli (EHEC) or Shigella [8,12-14]. EHEC causes at least 70 percent of cases of postdiarrheal HUS in the United States, and that 80 percent of these cases are caused by E. coli 0157:H7 [15]. In contrast, the majority of cases of postdiarrheal HUS in Australia are due tonon-0157 Shiga toxin producing E. coli. Epidemics of O157:H7 infection and HUS have become major health problems in the United States [16,17]. (See "Microbiology, pathogenesis, and epidemiology of enterohemorrhagic Escherichia coli".)
Unlike many other fecal isolates, E. coli O157:H7 ferments sorbitol slowly and can be screened for on sorbitol-MacConkey (SMAC) agar. Sorbitol-negative (translucent)colonies can be confirmed as E. coli biochemically and tested for reaction with antisera to the O157 antigen. Ninety-five percent of cultures positive for E. coli O157:H7 come from patients with visibly bloody stools or a history of bloody diarrhea. The rate of stool isolation is substantially higher in the first six days after onset of diarrhea.
Shigella dysenteriae type 1 associated HUS occurs in...
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