Hemolytic-uremic syndrome

Travelers' Diarrhea: A Clinical Review

BACKGROUND

Travelers' diarrhea is the most common travel-related malady. It affects millions of international travelers to developing countries annually and can significantly disrupt travel plans.

OBJECTIVE

To provide an update on the evaluation, diagnosis, treatment, and prevention of traveler's diarrhea.

METHODS

A PubMed search was completed in Clinical Queries using the key term "traveler's diarrhea". The search strategy included meta-analyses, randomized controlled trials, clinical trials, observational studies, and reviews. The search was restricted to English literature. Patents were searched using the key term "traveler's diarrhea" from www.freepatentsonline.com.

RESULTS

Between 10% and 40% of travelers develop diarrhea. The attack rate is highest for travelers from a developed country who visit a developing country. Children are at particular risk. Travelers' diarrhea is usually acquired through ingestion of food and water contaminated by feces. Most cases are due to a bacterial pathogen, commonly, Escherichia coli, and occur within the first few days after arrival in a foreign country. Dehydration is the most common complication. Pretravel education on hygiene and on the safe selection of food items is important in minimizing episodes. For mild travelers' diarrhea, the use of antibiotic is not recommended. The use of bismuth subsalicylate or loperamide may be considered. For moderate travelers' diarrhea, antibiotics such as fluoroquinolones, azithromycin, and rifaximin may be used. Loperamide may be considered as monotherapy or adjunctive therapy. For severe travelers' diarrhea, antibiotics such as azithromycin, fluoroquinolones, and rifaximin should be used. Azithromycin can be used even for the treatment of dysentery whereas fluoroquinolones and rifaximin cannot be used for such purpose. Recent patents related to the management of travelers' diarrhea are discussed.

CONCLUSION

Although travelers' diarrhea is usually self-limited, many travelers prefer expedient relief of diarrhea, especially when they are traveling for extended periods by air or ground. Judicious use of an antimotility agent and antimicrobial therapy reduces the duration and severity of diarrhea.

Managing acute abdominal pain in pediatric patients: current perspectives

Acute abdominal pain in pediatric patients has been a challenge for providers because of the nonspecific nature of symptoms and difficulty in the assessment and physical examination in children. Although most children with acute abdominal pain have self-limited benign conditions, pain may be a manifestation of an urgent surgical or medical condition where the biggest challenge is making a timely diagnosis so that appropriate treatment can be initiated without any diagnostic delays that increase morbidity. This is weighed against the need to decrease radiation exposure and avoid unnecessary operations. Across all age groups, there are numerous conditions that present with abdominal pain ranging from a very simple viral illness to a life-threatening surgical condition. It is proposed that the history, physical examination, laboratory tests, and imaging studies should initially be directed at differentiating surgical versus nonsurgical conditions both categorized as urgent versus nonurgent. The features of the history including patient’s age, physical examination focused toward serious conditions, and appropriate tests are highlighted in the context of making these differentiations. Initial testing and management is also discussed with an emphasis on making use of surgeon and radiologist consultation and the need for adequate follow-up and reevaluation of the patient.

Globotriaosylceramide (Gb3) content in HeLa cells is correlated to Shiga toxin-induced cytotoxicity and Gb3 synthase expression

Globotriaosylceramide (Gb3) and globotetraosylceramide (Gb4) are the proposed functional receptors for Shiga toxin (Stx). To elucidate the effect of Gb3 content on Stx-induced cytotoxicity in HeLa cells, we cloned HeLa cells and determined the correlation between glycolipids content and Stx-induced cytotoxicity. The 29 HeLa cell clone (HLCC) lines used showed a wide range of sensitivity to Stx, compared to Gb3-rich cells which were more sensitive, showing as little as 20% viability to 100 pg/ml Stx. In contrast, Gb3-deficient cells proved resistant as they were more than 80% viable to 100 ng/ml Stx. Gb3 content in the HLCC lines corresponded with Stxs-induced cytotoxicity as well as Gb3 synthase expression, but no correlation with Gb4 content was noted. These data show that Gb3 content, which is regulated by the expression of Gb3 synthase, determines the sensitivity of HeLa cells toward Stx.

Childhood hemolytic uremic syndrome is associated with adolescent-onset diabetes mellitus

Extra-renal manifestations of the hemolytic uremic syndrome in children are well described. Pancreatic involvement may manifest as transient hyperglycemia and permanent diabetes mellitus. Two previous case reports demonstrate short periods of "remission" between initial hyperglycemia and the development of permanent diabetes mellitus. We report an unusual case of a two-year-old Caucasian boy whose HUS-associated hyperglycemia resolved shortly after the acute phase of his illness only to recur as permanent diabetes mellitus at puberty. To our knowledge no other case is reported that demonstrates such a long interval between initial presentation and the development of permanent diabetes mellitus.

Curcumin decreases binding of Shiga-like toxin-1B on human intestinal epithelial cell line HT29 stimulated with TNF-alpha and IL-1beta: suppression of p38, JNK and NF-kappaB p65 as potential targets

Intestinal epithelial cells (IECs) have been known to produce galactose-alpha1,4-galactose-beta1,4-glucose ceramide (Gb3) which plays a pivotal role in the mucosal immune response. In particular, Shiga-like toxins (Stx) can induce apoptosis of IECs in the development of hemolytic uremic syndrome (HUS) through binding on Gb3. Therefore, it has been hypothesized that down-regulation of Gb3 (or binding of Stx) prevents Stx from damaging in IECs. This study investigated whether curcumin, having various biological properties such as being anti-bacterial, anti-viral and anti-cancer, could decrease binding of Stx and the related signal pathway. Curcumin significantly inhibited the binding of Stx and the production of Gb3 synthase (GalT6) mRNA in HT29 IECs stimulated with TNF-alpha and IL-1beta. Additionally, curcumin was able to inhibit mitogen-activated protein kinases (MAPKs), such as p38 and JNK, but not ERK1/2, degradation of IkappaB or translocation of NF-kappaB p65. Furthermore, curcumin significantly attenuated Stx-1 induced cell death and IL-8 expression. In summary, these data link Gb3 expression in HT29 cells stimulated with TNF-alpha and IL-1beta and suggest that blocking of Stx-binding by curcumin may prevent the Stx-associated HUS.

Traveler's diarrhea

Travelers' diarrhea is common. Between 8% and 50% of travelers develop diarrhea; incidence depends on the country visited. The attack rate is highest for travelers from a developed country who visit a developing country. Children are at particular risk. Travelers' diarrhea is usually acquired through ingestion of fecally contaminated food and water. Most cases are due to a bacterial pathogen, commonly, Escherichia coli, and occur within the first few days after arrival in a foreign country. More than 90% of episodes develop within the first 2 wk of initiation of travel. Dehydration is the most common complication. Water and electrolyte replenishment is important and can usually be accomplished with an oral rehydration solution. Judicious use of an antimotility agent and antimicrobial therapy reduces the duration and severity of diarrhea. Pretravel education on hygiene and on the safe selection of food items is important in minimizing episodes. Dukoraltrade mark (Aventis Pharma Ltd., Auckland, New Zealand) vaccine should be considered for travelers who are 2 y of age or older and who will be visiting an area associated with risk of infection due to enterotoxigenic E coli or Vibrio cholerae. Typhoid vaccine is recommended for travelers who will be visiting areas with poor sanitation and hygiene.

Epigallocatechin-3-gallate suppresses galactose-alpha1,4-galactose-1beta,4-glucose ceramide expression in TNF-alpha stimulated human intestinal epithelial cells through inhibition of MAPKs and NF-kappaB

Intestinal epithelial cells (IECs) have been known to produce galactose-alpha1,4-galactose-beta1,4-glucose ceramide (Gb3) that play an important role in the mucosal immune response. The regulation of Gb3 is important to prevent tissue damage causing shiga like toxin. Epigallocatechin-3-gallate (EGCG) has been studied as anti-carcinogenic, anti-oxidant, anti-angiogenic, and anti-viral activities, and anti-diabetic. However, little is known between the expressions of Gb3 on IECs. The aim of this study was to examine the inhibitory effect of EGCG, a major ingredient of green tea, on Gb3 production via mitogen-activated protein kinases (MAPKs) and nuclear factor-kappaB (NF-kappaB) in the TNF-alpha stimulated human colon epithelial cells, HT29. To investigate how Gb3 is regulated, ceramide glucosyltransferase (CGT), lactosylceramide synthase (GalT2), and Gb3 synthase (GalT6) were analyzed by RT-PCR in HT 29 cells exposed to TNF-alpha in the presence or absence of EGCG. EGCG dose-dependently manner, inhibits TNF-alpha induced Gb3 expression by blocking in both the MAPKs and NF-kappaB pathways in HT29 cells. TNF-alpha enhanced CGT, GalT2 and GalT6 mRNA levels and EGCG suppressed the level of these enzymes enhanced by TNF-alpha treatment.

Administration of ricin induces a severe inflammatory response via nonredundant stimulation of ERK, JNK, and P38 MAPK and provides a mouse model of hemolytic uremic syndrome

Recent interest in the health consequences of ricin as a weapon of terrorism has led us to investigate the effects of ricin on cells in vitro and in mice. Our previous studies showed that depurination of the 28S rRNA by ricin results in the inhibition of translation and the coordinate activation of the stress-activated protein kinases JNK and p38 MAPK. In RAW 264.7 macrophages, ricin induced the activation of ERK, JNK, and p38 MAPK, the accumulation of mRNA encoding tumor necrosis factor (TNF)-alpha, interleukin (IL)-1, the transcription factors c-Fos, c-Jun, and EGR1, and the appearance of TNF-alpha protein in the culture medium. Using specific inhibitors of MAPKs, we demonstrated the nonredundant roles of the individual MAPKs in mediating proinflammatory gene activation in response to ricin. Similarly, the intravenous administration of ricin to mice led to the activation of ERK, JNK, and p38 MAPK in the kidneys, and increases in plasma-borne TNF-alpha, IL-1beta, and IL-6. Ricin-injected mice developed the hallmarks of hemolytic uremic syndrome, including thrombotic microangiopathy, hemolytic anemia, thrombocytopenia, and acute renal failure. Microarray analyses demonstrated a massive proinflammatory transcriptional response in the kidneys, coincidental with the symptoms of hemolytic uremic syndrome. Therapeutic management of the inflammatory response may affect the outcome of intoxication by ricin.

Sex steroids do not affect shigatoxin cytotoxicity on human renal tubular or glomerular cells

BACKGROUND

The greater susceptibility of children to renal injury in post-diarrheal hemolytic-uremic syndrome (HUS) may be related, at least in part, to heightened renal cell sensitivity to the cytotoxic effect of Shiga toxin (Stx), the putative mediator of kidney damage in HUS. We hypothesized that sexual maturation, which coincides with a falling incidence of HUS, may induce a relatively Stx-resistant state in the renal cells.

METHODS

Cultured human glomerular endothelial (HGEN), human glomerular visceral epithelial (HGEC) and human proximal tubule (HPT) cells were exposed to Stx-1 after pre-incubation with progesterone, beta-estradiol or testosterone followed by determination of cytotoxicity.

RESULTS

Under basal conditions, Stx-1 potently and dose-dependently killed HPT and HGEC, but had relatively little effect on HGEN. Pre-incubation for 1, 2 or 7 days with physiologic or pharmacologic concentrations of progesterone, beta-estradiol or testosterone had no effect on Stx-1 cytotoxicity dose-response on any cell type. In addition, no steroid altered Gb3 expression (Stx receptor) by any cell type at any time point.

CONCLUSION

These data do not support the notion that hormonal changes associated with puberty induce an Stx-resistant state within kidney cells.

Lower gastrointestinal bleeding in children

Lower gastrointestinal bleeding is a common problem in the practice of general pediatrics. The differential diagnosis can be extensive and varies according to the age of the child. A specific diagnosis can usually be made with a thorough history, physical examination, simple laboratory investigations, and appropriate diagnostic studies. Treatment should be directed at the underlying cause. In most children, bleeding ceases spontaneously, and only supportive therapy is necessary. If there is evidence of hypovolemia, the patient must be hemodynamically stabilized, active bleeding stopped, and recurrent bleeding prevented.

Scarring resulting from chickenpox

Nine hundred and eighty-six children (519 boys, 467 girls) who had chickenpox at least 1 year previously were examined for the presence of scars resulting from this disease. Ninety-six (18.5%) boys and 88 (18.8%) girls had chickenpox scars, giving rise to an overall prevalence of 18.7%. The scars were found on the face in 75 (40.8%), neck 2 (1.1%), shoulders 8 (4.3%), upper limbs 15 (8.2%), anterior thorax 50 (27.2%), abdomen 106 (57.6%), back 65 (35.3%), buttocks 9 (4.9%), and lower limbs 12 (6.5%) affected children. The mean number of scars in the 184 children was 2.8 (standard deviation 1.9). The scars were hyperpigmented in 32, hypopigmented in 160, depressed in 38, and hypertrophic in 32 children. Keloids were noted in two children.

Effect of shigatoxin-1 on arachidonic acid release by human glomerular epithelial cells

BACKGROUND

Altered arachidonic acid (AA) metabolism has been implicated in the pathogenesis of renal injury in the hemolytic uremic syndrome (HUS). However, there is very little information of the effect of shigatoxin (Stx; the putative mediator of renal damage in HUS) on AA release or metabolism by renal cells. Since recent studies have demonstrated that glomerular epithelial cells (GECs) may be important early targets of Stx, the current study was undertaken to examine the effects of Stx on AA release and metabolism by GECs.

METHODS

Cultured human GECs were exposed to Stx1 +/- lipopolysaccharide (LPS) for 4 to 48 hours followed by determination of (3)H-arachidonate release, thromboxane A(2) (TxA(2)) and prostacyclin (PGI(2)) production, cyclooxygenase (COX) activity, and Western and Northern analyses for phospholipase A(2) (PLA(2)) and COX protein and mRNA levels, respectively.

RESULTS

Stx1 increased arachidonate release by GECs. LPS alone had no such effect, but increased arachidonate release in response to Stx1. Stx1-stimulated arachidonate release correlated with elevations in cPLA(2) and sPLA(2) protein and cPLA(2) mRNA levels. Stx1 also increased both TxA(2) and PGI(2) production by GECs; LPS alone did not alter eicosanoid production, but augmented Stx1 effects. Both Stx1 and LPS stimulated COX activity; however, these effects were not additive. Although there was an accompanying elevation of COX-1 and COX-2 mRNA, Stx1 decreased and LPS did not change COX1 and COX2 protein levels.

CONCLUSIONS

Stx1 alone or in conjunction with LPS increases arachidonate release and eicosanoid production by human GECs; this effect correlates with increased PLA(2) protein and mRNA levels. To our knowledge, this is the first study identifying the mechanisms of Stx1-stimulated AA release. These results raise the possibility that arachidonate release and metabolism by GECs, and conceivably other renal cell types, are involved in renal injury in HUS.

Haemolytic uraemic syndrome

Diarrhoea-associated haemolytic uraemic syndrome develops in about 5 to 10% of children with haemorrhagic colitis due to Escherichia coli (E. coli) O157:H7 and is a common cause of acute renal failure in childhood. Endothelial cell damage, white blood cell activation and platelet-endothelial cell interactions are important in the pathogenesis. Meticulous supportive care, with attention to nutrition and fluid, and electrolyte balance, is important. Dialysis is necessary in many children. Public health follow-up is important to minimise the spread of E. coli O157:H7, which is transmitted by person-to-person, as well as through contaminated food products. 20-year follow-up studies report that 75% of children recover without any clinically significant long term sequelae. Chronic renal failure is reported in about 5% of children.

Cytotoxic effect of Shiga toxin-1 on human glomerular epithelial cells

BACKGROUND

Shiga toxin-1 (Stx-1) has been implicated in the pathogenesis of postdiarrheal hemolytic-uremic syndrome (Stx HUS). Endothelial cells had been felt to be the primary renal target of Stx-1; however, recent studies suggest that renal epithelial cells may also be responsive. To further examine this issue, we evaluated the responsiveness of human glomerular epithelial cells (GECs) to the cytotoxic effects of Stx-1.

METHODS

Cultured GECs were exposed to Stx-1 in the presence and absence of a variety of inflammatory factors likely to be elevated in the kidney or serum of patients with Stx HUS. Cell survival, protein synthesis, total cell Gb3 levels and synthesis, and Stx-1 binding were measured.

RESULTS

GECs were sensitive to Stx-1, with an LD50 of approximately 10-7 g/L (1.4 pmol/L). Interleukin-1 (IL-1), lipopolysaccharide (LPS), tumor necrosis factor-alpha (TNF-alpha), and butyrate increased Stx-1 cytotoxicity and total cell Gb3 levels. These agents, with the exception of TNF-alpha, also increased Stx-1 binding to GECs. IL-6 failed to alter Stx-1 toxicity, binding, or Gb3 content.

CONCLUSIONS

These studies indicate that GECs are sensitive to the cytotoxic effects of Stx-1 and that inflammatory factors can increase toxin responsiveness. GECs may be a target of Stx-1 action in Stx HUS.

Escherichia coli O157:H7-induced hemolytic-uremic syndrome: histopathologic changes in the colon over time

The 1993 E. coli O157:H7 epidemic in the Western United States has provided a unique opportunity to evaluate the histopathologic temporal progression of disease in the colon in children who developed hemolytic uremic syndrome (HUS). In this report we briefly summarize the clinical courses of eight patients and then discuss the colonic pathology observed in specimens obtained at surgery or at the time of autopsy. The patients were divided into two groups: group 1 consisted of six subjects whose colonic samples were obtained during the acute phase of disease, and group 2 consisted of two subjects whose samples were obtained late in their disease. Both the gross and microscopic findings showed that the most severely affected as well as the earliest affected regions of the colon were the left and transverse portions. Only later in the disease progression was there right-sided colon involvement. These findings are in contrast to the distribution described in E. coli O157:H7 hemorrhagic colitis without HUS, thus suggesting a different mechanism of injury.

Evaluating the child with proteinuria

Proteinuria is a common laboratory finding in children. It might represent a benign condition or herald the presence of a serious underlying renal disease or systemic disorder. Investigation to confirm a diagnosis or seek reassurance is important. This paper discusses the various causes of proteinuria, and those aspects of the history, physical examination, and the laboratory tests that will help determine the cause or reassure that a serious problem is not currently present.

Infarction of the choledochus, liver, gallbladder, and pancreas: a unique complication of the hemolytic uremic syndrome

Hemolytic uremic syndrome (HUS) is associated with multiple nonrenal manifestations. A unique case is described of a 3-year-old boy who presented with a classic diarrheal prodrome followed by massive necrosis of the biliary tree and common bile duct, pancreas, and the left lobe of his liver. This complication of HUS has not been reported in the English-language literature.

Shiga toxin-1 regulation of cytokine production by human proximal tubule cells

BACKGROUND

Interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor (TNF) levels are elevated in kidneys of patients with post-diarrheal hemolytic uremic syndrome (D+HUS) and may contribute to renal dysfunction. The renal cellular sources of these inflammatory cytokines in D+HUS are largely unknown, however, the proximal tubule has emerged as a potentially important candidate. Since Shiga toxin-1 (Stx-1) has been implicated in the genesis of D+HUS, we examined the effect of Stx-1 on cytokine production by human proximal tubule cells.

METHODS

Stx-1 cytotoxicity, protein synthesis inhibition, and effect on IL-1, IL-6, and TNF protein release and mRNA levels were determined. The effect of another protein synthesis inhibitor, cycloheximide (CHX), on these parameters was also evaluated.

RESULTS

Stx-1 greatly increased TNF release and mRNA levels while CHX, at concentrations that produced similar inhibition of protein synthesis, had no effect on TNF production. In contrast, Stx-1 and CHX caused comparable elevations in IL-1 release and mRNA accumulation. Stx-1 and CHX also stimulated IL-6 mRNA accumulation, but only at concentrations that either were cytotoxic or substantially blocked protein synthesis. Finally, lipopolysaccharide, which is likely to be elevated in the circulation of patients with D+HUS, had no effect alone, but synergized with Stx-1 to increase IL-1 production.

CONCLUSIONS

These results indicate that Stx-1 stimulates proximal tubule inflammatory cytokine production and that this effect is due partially to nonspecific induction of mRNA levels as well as activation of Stx-1-specific mechanisms.

Neurotoxicity of intrathecal Shiga toxin 2 and protection by intrathecal injection of anti-Shiga toxin 2 antiserum in rabbits

The initial brain lesions in rabbits given intravenous Shiga toxin 2 (Stx2) were noted at 24 h in an area around the third ventricle (Fujii et al., Infect Immun 1996, 64: 5053-60). This result implied that Stx2 is present in the cerebrospinal fluid (CSF) despite the fact that the toxin was administered intravenously. We measured Stx2 activity in CSF by using a Vero cell cytotoxicity assay at various times after an intravenous injection of Stx2. Stx2 was detected from 2 h after the injection, and its concentration in CSF remained at a high level for a further 6 h. Fifty percent lethal doses (LD 50) of Stx2 were measured in rabbits after intravenous and intrathecal Stx2 injections; The LD 50 after an intrathecal injection of Stx2 was 0. 36 microg/kg, which was 9.2-fold lower than that of an intravenous injection of Stx2 (3.4 microg/kg). Magnetic resonance images obtained after an intrathecal Stx2 injection (5 microg/kg) were compared with those obtained after an intravenous Stx2 injection (5 microg/kg). At 48 h, the cerebellar lesions had spread from the area in contact with the CSF on a T2-weighted image, which suggests that the intrathecal Stx2 may invade the cerebellum directly. We then examined whether anti-Stx2 antiserum injected intrathecally protects rabbits against brain damage. Eighty percent of the rabbits infected with Stx2 at 5 microg/kg died within 8 days from brain damage. Rabbit anti-Stx2 sera (with titres of x16 and x64 by the Ouchterlony precipitation method) were administered into the CSF space through the cisterna magna. All the rabbits ( n=10) survived when they were given an intrathecal injection of rabbit anti-Stx2 antiserum 2 h before the intravenous injection of Stx2. Our results suggest that a leakage of Stx2 into the CSF from the choroid plexus causes brain damage, and that an intrathecal injection of anti-Stx2 antiserum could be a therapy for acute encephalopathy caused by Stx2-producing Escherichia coli.

Acute renal failure in infants, children and adults

Acute renal failure (ARF) occurs in many critically ill patients regardless of age. A combination of events often seen in critical care settings, including shock, sepsis, hypoxia, and the use of potentially nephrotoxic medications, combine to make ARF an ongoing and important management issue in critical care medicine. Since the events leading to the development of ARF differ in infants, children, adults, and the elderly, the pathophysiology, clinical features, and treatment modalities do indeed have remarkable similarities among the different age groups.

[Digestive manifestations in hemolytic uremic syndrome in children]

BACKGROUND

Gastro-intestinal manifestations are relatively frequent during the course of hemolytic uremic syndrome (HUS), some of them requiring special supportive care. This work was aimed at retrospectively studing gastrointestinal manifestations of HUS and determining their place in the prognosis.

PATIENTS

Thirty-seven children aged 4 months to 11 years (22 girls and 15 boys) were included in the study.

RESULTS

All children but one had gastrointestinal prodromes. During the course of HUS, various manifestations were seen: bloody diarrhea in 32% of patients, ileo-ileal intussusception in 3%, rectal prolapse in 8% and hepatic cytolysis in 38%. Seven patients with bloody diarrhea had a complicated course, lethal in one. Comparison between these seven children and the 30 others revealed some indicators of severe gut involvement: female sex, short duration of gastrointestinal prodromes, hemorrhagic colitis with rectal prolapse, high WBC count, high neutrophils count and less important degree of anemia at admission. Severity of the gastrointestinal lesions was correlated with that of the outcome of the renal disease.

CONCLUSION

Gastrointestinal tract is frequently affected in HUS and severe complications can appear, potentially leading to death. Total parenteral nutrition could prevent occurrence of gastrointestinal complications. Severe gastrointestinal lesions are associated with a poor renal outcome.

Hemostatic complications in renal disorders of the young

This review focuses on the hemorrhagic and thrombotic complications sometimes associated with the most common renal disorders in children. A Medline search of the literature was conducted from 1966 to January 1995, using combinations of key words appropriate for each disorder. Additional references were located through the bibliographies of the publications and recent journals were searched independently. The most common renal disorders with hemostatic complications in children were: renal vein thrombosis (268 children in 80 publications), hemolytic uremic syndrome (473 children in 29 publications), nephrotic syndrome (4,158 children in 51 publications), renal transplantation (3,976 children in 14 publications), glomerulonephritis (20 publications), end-stage renal disease, and dialysis (22 publications). The age distribution, clinical presentation, etiology, diagnosis, treatment, and outcome of the affected children were analyzed for each disorder. Children with inherited pre-thrombotic disorders usually do not present during childhood unless there is a secondary risk factor. Similarly, most children with renal disease do not develop thromboembolic complications. Therefore, when a child with a renal disorder develops a thromboembolic event, evaluation for an inherited pre-thrombotic disorder should be seriously considered. Guidelines for the use of heparin and warfarin in these children (both therapeutically and prophylactically) are given. At this time, the risk/benefit of thrombolytic therapy in children is not known and a general recommendation for thrombolytic therapy cannot be made.

The hemolytic uremic syndrome

HUS is the most common cause of acute renal failure in infants and young children and follows a diarrheal prodrome about 90% of the time. Persuasive evidence shows that virtually all of postdiarrheal cases are caused by EHEC infections, and that the great majority of cases in the United States are caused by the EHEC serotype O157:H7. Mortality is approximately 5%, and approximately 10% of survivors are left with severe sequelae. A much larger number (30%-50%) experience mild chronic renal damage. Public health strategies, including zero tolerance for fecal contamination in slaughter houses and additional public education on proper food handling and cooking, does much to decrease the prevalence of the syndrome. Efforts to further dissect the postdiarrheal pathogenic cascade should continue, and an animal model needs to be developed. Only then will researchers be positioned to develop effective intervention strategies. Preventing life-threatening extrarenal complications, especially of the CNS, is a major challenge. Idiopathic nondiarrheal HUS accounts for approximately 10% of cases and comprises a poorly understood composite of HUS subsets. Research directed toward a better understanding of these mysterious variants also is a priority for the years ahead.

Indirect hemagglutination assay for antibodies to Escherichia coli lipopolysaccharides O157, O111 and O26 in patients with hemolytic uremic syndrome

We examined sera from 10 patients with hemolytic uremic syndrome (HUS) and 51 controls, with and without diarrhea, for antibodies to Escherichia coli lipopolysaccharides (LPS) O157, O111 and O26 using the indirect hemagglutination (IHA) assay. A significant rise (to a titer of > or = 2560) in IHA antibody to O157 LPS was detected in eight of the 10 HUS patients, to O111 in two patients, one of whom showed concomitantly an antibody rise to O157, but to O26 in no patients. The IHA titers fell rapidly after the acute phase of the illness. Of the control sera 15 (29.4%) non-specifically agglutinated uncoated sheep red blood cells (SRBC) at a titer of > or = 80, six (3.9%) at > or = 320 and the maximum was 640. In spite of the relatively low level of non-specific agglutination the IHA appeared to be a useful screening method to identify verotoxin-producing E. coli infections at the early stage of HUS because the titers were clearly higher than non-specific agglutination and the assay is easy to perform and gives results quickly. Artificial carriers are being considered for use in place of SRBC to diminish the non-specific hemagglutination.

Racial incidence of hemolytic uremic syndrome

Hemolytic uremic syndrome (HUS) is the most common cause of acute renal failure in children and is caused by infection with verotoxin-producing Escherichia coli. There is no consensus on the relative incidence of HUS in blacks and whites. An equal racial incidence has been reported by two centers with small black populations. A series from Washington D.C. reported a low incidence in blacks. The population of Alabama is 32% black and 66% white. The Children's Hospital of Alabama admission rate has a similar racial distribution (35% black, 65% white). A record review from 1980-1992 identified 45 patients with HUS; 43 (96%) were white and only 2 (4%) were black. Based on census data for Alabama in 1980 and 1990, this gives an average annual incidence of HUS of 0.45 per 100,000 in whites and of 0.043 per 100,000 in blacks (P < 0.001, Fischer's exact test). Similar results were found in the group of patients with HUS and a history of diarrhea; whites 0.39 and blacks 0.02 (P < 0.001). However, in those with no history of diarrhea there was no significant racial difference: whites 0.05 and blacks 0.02. There were too few blacks to compare clinical course and outcome. We conclude that typical diarrhea-associated HUS is a relatively rare disease in blacks compared with whites. The reasons are unclear.