Epidemiology of hemolytic-uremic syndrome in Canadian children from 1986 to 1988. The Canadian Pediatric Kidney Disease Reference Centre

Antibody response to Shiga toxins Stx2 and Stx1 in children with enteropathic hemolytic-uremic syndrome

A Western blot (immunoblot) assay (WBA) for the detection of immunoglobulin G antibodies to Shiga toxins Stx2 and Stx1 in sera from 110 patients with enteropathic hemolytic-uremic syndrome (53 culture confirmed to have Shiga toxin-producing Escherichia coli [STEC] infection) and 110 age-matched controls was established by using a chemiluminescence detection system. Thirty-nine (74%) of the 53 culture-confirmed cases were infections with STEC serotype O157, and 14 (26%) were associated with infection by other STEC serotypes. The frequency of an anti-Stx2 response following infection by a Stx2-producing strain (34 of 48 cases; 71%) was higher than that of an anti-Stx1 response following Stx1-producing STEC infection (4 of 10). Furthermore, the frequency of an anti-Stx2 response in 110 control sera (10%) was significantly higher than the frequency of an anti-Stx1 response (1.8%) (P = 0.0325). For STEC O157 culture-confirmed cases WBA for toxin detection had a diagnostic sensitivity of 71% and a specificity of 90%. Because of its high specificity the assay might be a helpful tool for diagnosing suspected STEC infection when tests of stool samples or serological tests against various lipopolysaccharide antigens are negative. Furthermore, the prevalence of anti-Stx antibodies in healthy controls probably reflects the population immunity to systemic Stx-associated disease. It can thus serve as a basis for comparing immunity levels in different populations and for considering future Stx toxoid immunization strategies.

Enteric and foodborne disease in children: A review of the influence of food- and environment-related risk factors

Canadian statistics show that children from birth to four years of age are more likely to be reported with an infection from Campylobacter, Giardia, Salmonella and Shigella species, and verotoxigenic Escherichia coli than any other age group. A review of the Canadian and international literature, and an analysis of case and outbreak data suggest that the risk factors for infection in young children (ages birth to four years) are different from the risk factors for older children and adults. In children from birth to four years of age, infant formula, fast foods, snacks and candies have caused major outbreaks of enteric and foodborne diseases; however, the contamination of a child's environment or the presence of ill individuals in a household may be highly significant to disease expression. Contact with animals (including family pets) and contaminated surfaces, together with experimental touching and testing behaviours, are important routes of infection for infants and preschool children. Risk factors for enteric infections in children appear to be related, occasionally, to specific foods that are particularly attractive to all children (all age groups from infants up to and including elementary school-aged childen), to an infected person or pet in the same household, or to the contamination of a child's environment. Nonfood-related risk factors may be of particular significance in infection in infants and very young children. Contact with animals, particularly exotic pets and farm animals, or their environments should be considered to be a potential source of infection in children in situations in which there is an absence of other risk factors. The evidence presented in the current paper emphasizes the importance of personal and home hygiene practices in limiting children's exposure to enteric pathogens. Strict hand washing practices and restrictions on touching birds, reptiles and other animals at petting zoos or in nursery and primary school facilities are recommended to avoid widespread infection. Public health authorities should consider the development of guidelines on the provision of hand washing facilities and instruction notices in settings where the public may come into contact with farm or other animals in jurisdictions where such guidelines do not already exist.

Adsorption effect of activated charcoal on enterohemorrhagic Escherichia coli

The adsorption property of activated charcoal on verotoxin (VT)-producing Escherichia coli (VTEC) was examined using E. coli O157:H7. In the present study, E. coli O157:H7 strains were effectively adsorbed by activated charcoal. Adsorption was dose-dependent, and the maximum adsorption occurred within 5 min. At 10 mg of activated charcoal, bacteria tested were completely adsorbed. Activated charcoal also had the capacity to adsorb toxin (verotoxin 2) activity from the bacterial extract. Furthermore, the adsorption efficiency of activated charcoal for the normal bacterial flora in the intestine was assessed using Enterococcus faecium, Bifidobacterium thermophilum, and Lactobacillus acidophilus. Activated charcoal showed lower binding capacity to the normal bacterial flora tested than that to E. coli O157:H7 strains. These results suggest that activated charcoal could be a good adsorbent system for the removal of VTEC and verotoxin.

Relationship between susceptibility to hemolytic-uremic syndrome and levels of globotriaosylceramide in human sera

The relationship between differential susceptibility to hemolytic-uremic syndrome (HUS) and levels of globotriaosylceramide (Gb3) in serum was studied in patients infected with verotoxin-producing Escherichia coli (VTEC). The serum Gb3 levels in patients with HUS were lower than these in diarrheal patients without subsequent HUS or in patients without clinical symptoms, indicating that individuals with a lower content of serum Gb3 show a higher incidence of HUS following VTEC infection.

Increased plasma thrombomodulin as a vascular endothelial cell marker in patients with thrombotic thrombocytopenic purpura and hemolytic uremic syndrome

Several hemostatic and vascular endothelial cell markers were measured in 39 patients with thrombotic thrombocytopenic purpura (TTP)/hemolytic uremic syndrome (HUS) and in 20 healthy volunteers to examine the relationship between the occurrence of hemostatic abnormality or vascular endothelial cell injury and patient outcome. The plasma levels of von Willebrand factor, tissue plasminogen activator (TPA), plasminogen activator inhibitor (PAI-1), and the TPA-PAI-1 complex were significantly increased in TTP/HUS patients; however, the levels of these markers were not significantly different between TTP/HUS patients who survived and those who died, suggesting that these markers might not be directly related to outcome. The plasma levels of soluble granule membrane protein (GMP)-140 were significantly higher in TTP/HUS patients than in healthy volunteers, suggesting that platelets and vascular endothelial cells are activated or injured in TTP/HUS. There was no significant difference in GMP-140 levels between TTP/HUS patients with good and poor prognoses; this may be owing to the release of GMP-140 from platelets. The plasma thrombomodulin (TM) levels in TTP/HUS patients were significantly higher than in healthy volunteers; the plasma TM levels were significantly higher in patients who died than in patients who survived. These findings showed that TM levels reflect the outcome and that the outcome of TTP/HUS depends on the presence vascular endothelial cell injury. The plasma protein C and antithrombin levels were markedly reduced in TTP/HUS patients who died compared with those who survived. These findings suggest that reduced plasma antithrombin and protein C may be useful markers of systemic vascular endothelial injury. In conclusion, the results of this study showed that the outcome of TTP/HUS is related to vascular endothelial cell injury and that plasma TM, antithrombin, and protein C levels may be useful markers of systemic vascular endothelial cell injury.

Inhibitory effect of intestinal anti-Gb3 IgA antibody on verotoxin-induced cytotoxicity

The effect of intestinal IgA antibody against the receptor for verotoxin (VT), globotriaosylceramide (Gb3), on VT-mediated cytotoxicity was examined. Intestinal IgA antibodies against Gb3 were prepared by oral immunization of mice with Gb3 and adjuvant monophosphoryl lipid A (MPL)-containing liposomes composed of dipalmitoylphosphatidylcholine, dipalmitoylphosphatidylserine and cholesterol (1 : 1 : 2, molar ratio) (PS-liposome). Oral administration with Gb3 and MPL-containing PS-liposome induced significant IgA responses to Gb3 in the intestinal lavage fluid in all mice tested. Furthermore, anti-Gb3 IgA antibodies in the lavage fluid effectively inhibited the cytotoxicity of VT2 to Vero cells in a dose-dependent manner. These results suggest that anti-Gb3 IgA antibodies produced in the intestinal tract, upon oral immunization with Gb3-containing liposome, function as inhibitors against VT and also indicate the potential usefulness of oral PS-liposome vaccines containing MPL for the induction of a protective mucosal immune response against intestinal diseases.

Soluble Fas and soluble Fas-ligand in children with Escherichia coli O157:H7-associated hemolytic uremic syndrome

We measured soluble Fas-ligand (sFas-L) and soluble Fas (sFas) levels by sandwich enzyme-linked immunosorbeny assay and compared them among (1) healthy controls (n = 11), (2) children with hemorrhagic colitis (HC) caused by a non-verotoxin-producing pathogen (n = 23), (3) patients with uncomplicated Escherichia coli O157:H7 HC (n = 14), and (4) children with O157:H7-associated hemolytic uremic syndrome (HUS) (n = 24). Children with uncomplicated E coli O157:H7 HC and HUS were matched for duration of enteric prodrome before blood sample collection. We also compared sFas-L and sFas levels among patients with HUS according to severity of renal dysfunction; abnormally increased sFas-L levels were noted in only 4% of the children (n = 3). Abnormally high concentrations of sFas were noted in 9% of the children with HC caused by a non-verotoxin-producing pathogen, 29% of the patients with uncomplicated E coli O157:H7 HC, and 69% of the children with O157:H7-associated HUS. Compared with healthy controls, patients with HUS had twofold greater concentrations of sFas (P: < 0.0001). Levels of sFas were not statistically different between 14 patients with uncomplicated O157:H7 HC and 14 children with HUS (8.2 +/- 4.7 versus 11.0 +/- 4.6 U/mL, respectively; P: < 0.07) when matched for time after onset of enteritis (7.0 +/- 3.7 versus 7.3 +/- 3.8 days, respectively). Greater concentrations of sFas were noted in patients with HUS who developed oligoanuria (n = 10; P: < 0.007), required peritoneal dialysis (n = 10; P: < 0.007), or had a decreased glomerular filtration rate (n = 5; P: < 0.002) 1 year later. Our data show that plasma concentrations of sFas but not sFas-L are abnormally increased in children with O157:H7 infections. Levels of sFas are associated with severity of renal dysfunction during HUS. Further studies are needed to clearly determine the role and origin of circulating sFas among children with infections caused by E coli O157:H7.

Verotoxin targets lymphoma infiltrates of patients with post-transplant lymphoproliferative disease

Post-transplant lymphoproliferative disease (PTLD) is an invasive, EBV expressing B lymphoma and a major cause of morbidity and mortality following organ transplantation. Presently there is limited therapy available; rather the patient often loses the allograft or succumbs to the malignancy. CD77 (or globotriaosyl ceramide -Gb(3)) is a germinal center B cell marker [Gregory et al. Int J Cancer 1998;42:213-20; Gregory et al., J Immunol 1987;139:313-8; Mangeney et al. Eur J Immunol 1991;21:1131-40], expressed on most EBV infected B cells and is the receptor for the E. coli derived verotoxin (VT) [Lingwood CA. Advances in Lipid Research 1993;25:189-212]. We present the basis of a possible novel approach to PTLD therapy utilizing the specific targeting of VT to the infiltrating lymphoma cells. Biopsies of adenoid, kidney or liver tissue of four PTLD patients were stained with verotoxin to determine expression of CD77. VT is a potent inducer of necrosis/apoptosis of receptor positive cells. In each PTLD case, the infiltrating EBV positive B lymphoma cells were strongly and selectively stained with VT, identifying CD77 as a new marker for these cells. For such individuals, VT might provide the basis of an approach to control their malignancy.

Cattle lack vascular receptors for Escherichia coli O157:H7 Shiga toxins

Escherichia coli O157:H7 causes Shiga toxin (Stx)-mediated vascular damage, resulting in hemorrhagic colitis and the hemolytic uremic syndrome in humans. These infections are often foodborne, and healthy carrier cattle are a major reservoir of E. coli O157:H7. We were interested in knowing why cattle are tolerant to infection with E. coli O157:H7. Cattle tissues were examined for the Stx receptor globotriaosylceramide (Gb(3)), for receptivity to Stx binding in vitro, and for susceptibility to the enterotoxic effects of Stx in vivo. TLC was used to detect Gb(3) in tissues from a newborn calf. Gb(3) was detected by TLC in kidney and brain, but not in the gastrointestinal tract. Immunohistochemistry was used to define binding of Stx1 and Stx2 overlaid onto sections from cattle tissues. Stx1 and Stx2 bound to selected tubules in the cortex of the kidney of both newborn calves (n = 3) and adult cattle (n = 3). Stx did not bind to blood vessels in any of the six gastrointestinal and five extraintestinal organs examined. The lack of Gb(3) and of Stx receptivity in the gastrointestinal tract raised questions about the toxicity of Stx in bovine intestine. We found that neither viable E. coli O157:H7 nor Stx-containing bacterial extracts were enterotoxic (caused fluid accumulation) in ligated ileal loops in newborn calves. The lack of vascular receptors for Stx provides insight into why cattle are tolerant reservoir hosts for E. coli O157:H7.

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.

Leukocytosis in children with Escherichia coli O157:H7 enteritis developing the hemolytic-uremic syndrome

BACKGROUND

Fewer than 10% of children with Escherichia coli O157:H7 enteritis develop hemolytic-uremic syndrome (HUS).

OBJECTIVE

To determine whether circulating leukocytes are independent risk markers of developing HUS during E. coli O157:H7 enteritis.

METHODS

We reviewed the charts of all children with culture-proved E. coli O157:H7 infections seen at Sainte-Justine Hospital between 1987 and 1997. Epidemiologic data, laboratory indices and circulating leukocytes counts were noted. HUS diagnosis was validated with independent HUS patient lists from the pediatric nephrology services of tertiary care hospitals in the Montreal metropolitan area. The date of onset of enteritis was determined by two independent observers. Leukocyte counts were compared among the following independent groups: (1) uncomplicated O157:H7 enteritis (Group 1); (2) O157:H7 enteritis with the subsequent development of HUS (Group 2); (3) HUS already present at the time of medical consultation (Group 3).

RESULTS

There were 369 children with E. coli O157:H7 infection. A complete blood count was not performed in 114 (31%) patients. Observers disagreed on the date of onset of gastroenteritis in 34 (9%) children only (kappa 0.92). The study population thus included 221 patients: Group 1, n = 161; Group 2, n = 27; and Group 3, n = 33. Patients developing HUS (Group 2) presented greater total leukocyte (P < 0.008), polymorphonuclear (P < 0.008) and monocyte (P < 0.07) counts than those with an uncomplicated course (Group 1). Logistic regression analysis showed that young age [odds ratio (OR), 0.98; 95% confidence interval (CI), 0.96 to 0.99], duration of enteric prodrome < or =3 days (OR 4.8, 95% CI 1.13 to 20.7) and initial leukocytosis (OR 1.22, 95% CI, 1.11 to 1.35) were independent predictors of HUS.

CONCLUSIONS

Based on the variables identified above, further studies are needed to determine whether the inflammatory response of the host represents only a marker of the severity of gastrointestinal infection or whether, alternatively, it is a pathophysiologic factor that leads to HUS.

Thrombotic thrombocytopenic purpura-hemolytic uremic syndrome: diagnosis and management

Thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS) is a clinical syndrome defined by the presence of thrombocytopenia and microangiopathic hemolytic anemia without a clinically apparent etiology. Patients may also have multiple other symptoms and signs including neurologic and renal abnormalities and fever. In the era prior to effective therapy with plasma exchange, most patients developed multisystem abnormalities and the syndrome was more easily recognized. Now, since there is urgency to begin treatment, sufficient diagnostic criteria for TTP-HUS are only thrombocytopenia and microangiopathic hemolytic anemia without a clinically apparent cause; patients may have no neurologic symptoms, renal abnormalities, or fever. This has lead to an apparent increased incidence because of both the increased importance of early recognition and the decreased specificity of the diagnostic criteria. Effective treatment has also revealed new aspects of the clinical course of TTP-HUS following the initial response to plasma exchange treatment: prompt exacerbations, which are common when plasma exchange is diminished in frequency or discontinued, and later relapses, which may occur many years after the initial episode. This review describes the evolution of the syndrome of TTP-HUS in the current era of effective treatment, and describes the management and clinical outcomes among patients treated by the Oklahoma Blood Institute.

Circulating levels of transforming growth factor-beta1 and lymphokines among children with hemolytic uremic syndrome

Verotoxin-producing Escherichia coli (VTEC) cause hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS). The aim of this study was to compare the circulating levels of transforming growth factor-beta 1 (TGF-beta1), T helper (T(H))1 (interferon [IFN]-gamma, interleukin [IL]-2), and T(H)2-associated lymphokines (IL-4, IL-13) in children with uncomplicated Escherichia coli O157:H7 HC and patients who developed HUS. Circulating levels of IL-2, IL-4, and IL-13 were undetectable, and those of IFN-gamma were low and comparable among groups. Concentrations of TGF-beta1 were higher in children with uncomplicated O157:H7 HC than among those who developed HUS (934 +/- 680 versus 514 +/- 497 pg/mL, respectively; P < 0.04). The circulating levels of TGF-beta1 were also higher among children who did not take antidiarrheal agents (P < 0.008) and those who have been immediately discharged from the emergency room (P < 0.03). Our results did not show an imbalanced T(H)1/T(H)2-associated lymphokine response during the development of HUS. Increased circulating levels of TGF-beta1 in children with milder O157:H7 or uncomplicated HC most likely reflect appropriate intestinal tissue repair mechanisms rather than a remote systemic endocrine effect on the kidneys.

Glycolipid receptors for verotoxin and Helicobacter pylori: role in pathology

Eukaryotic cell surface glycolipids can act as both the primary interface between bacteria and their host and secondly as a targeting mechanism for bacterial virulence factors. The former is characterized by redundancy in adhesin-receptor interactions and the latter by a higher affinity, more restrictive glycolipid binding specificity for targeting. Interactions of verotoxin with its glycolipid receptor globotriaosylceramide and Helicobacter pylori binding to a variety of different glycolipids, which can be environmentally regulated, provide examples of these differing modes of glycolipid receptor function. Verotoxins are involved in endothelial targeting in the microangiopathies of hemorrhagic colitis and hemolytic uremic syndrome (HUS). The highly restricted binding specificity and crystal structure of the verotoxin B subunit have allowed theoretical modeling of the Gb3 binding site of the verotoxin B subunit pentamer which provides an approach to intervention. Studies of the role of glycolipid function in verotoxin-induced disease have concentrated on the distribution of Gb3 and its ability to mediate the internalization of the toxin within the target cell. The distribution of Gb3 within the renal glomerulus plays a central role in defining the age-related etiology of HUS following gastrointestinal infection with VT producing Escherichia coli. H. pylori, on the other hand, instigates a less distinct but more complex disseminated gastric inflammation. Studies on the role of glycolipid receptors in H. pylori infection have been bogged down in establishing the importance of each binding specificity defined. In addition, the physiological condition of the organism within the various binding assays has not been extensively considered, such that spurious non-physiological interactions may have been elucidated. The identification and cloning of a Le(b) binding adhesin and the identification of cell surface hsp70 as a mediator of sulfoglycolipid binding under stress conditions may now allow a more molecular approach to define the role of glycolipid recognition in this infection.

Diarrheogenic Escherichia coli

The diarrheogenic E coli are currently difficult to diagnose and treat. For physicians in the United States, they are primarily a concern in children returning from international travel. The exception to this generalization is STEC, which, because of the low inoculum, ease of transmission, and serious consequences, are important pathogens in the United States.

Outcome of thrombotic thrombocytopenic purpura and hemolytic uremic syndrome in Japan

We examined 159 patients with thrombotic thrombocytopenic purpura and hemolytic uremic syndrome in Japan. The subjects were divided in three groups; 90 patients with thrombotic thrombocytopenic purpura, 51 patients with verotoxin-induced hemolytic uremic syndrome, and 18 patients with drug-induced hemolytic uremic syndrome. Eighty-two percent of the patients with thrombotic thrombocytopenic purpura had associated neurological disorders and 78% of drug-induced hemolytic uremic syndrome associated with pulmonary edema. Renal insufficiency was noted in the 69% cases with both hemolytic uremic syndrome groups. Seventeen patients with thrombotic thrombocytopenic purpura had systemic lupus erythematosus and 6 were pregnant. Autoantibody were positive in 53% of thrombotic thrombocytopenic purpura. Seventy-seven percent of patients with thrombotic thrombocytopenic purpura received plasma exchange at 4,000 mL/day three times a week, 71% antithrombotic agents, and 78% steroid administration, respectively. However, 27% of the patients with hemolytic uremic syndrome were treated by hemodialysis in addition to antithrombotic agents. When drug-induced hemolytic uremic syndrome was diagnosed, the drug was immediately discontinued and the patients were treated with antiplatelet agents. Seventy-four percent of the patients with thrombotic thrombocytopenic purpura were alive at 26 weeks compared with 95% of those with hemolytic uremic syndrome. As thrombotic thrombocytopenic purpura had a high mortality rate in Japan, we should carry out early diagnosis and early treatment.

Flow-through immunofiltration assay system for rapid detection of E. coli O157:H7

A flow-through amperometric immunofiltration assay system based on disposable porous filter-membranes for rapid detection of Escherichia coli O157:H7 has been developed. The analytical system utilizes flow-through, immunofiltration and enzyme immunoassay techniques in conjunction with an amperometric sensor. The parameters affecting the immunoassay such as selection of appropriate filter membranes, membrane pore size, antibody binding capacity and the concentrations of immunoreagents were investigated and optimized. Non-specific adsorption of the enzyme conjugate was investigated and minimized. A sandwich scheme of immunoassay was employed and the immunofiltration system allows to specifically and directly detect E. coli cells with a lower detection limit of 100 cells/ml. The working range is from 100 to 600 cells/ml with an overall analysis time of 30 min. No pre-enrichment was needed. This immunosensor can be easily adapted for assay of other microorganisms and may be a basis for a new class of highly sensitive bioanalytical devices for rapid quantitative detection of bacteria.

Escherichia coli O157:H7 gastroenteritis and the hemolytic uremic syndrome: an emerging infectious disease

Escherichia coli O157:H7 is an increasingly common cause of a variety of illnesses, including bloody diarrhea and the hemolytic uremic syndrome. This emerging infectious agent was first identified in 1982 and has been isolated with increasing frequency since then. This chapter reviews the epidemiology, clinical spectrum, diagnosis, treatment, and prevention of infections with E. coli O157:H7.

Neuropsychological sequelae of haemolytic uraemic syndrome. Investigators of the HUS Cognitive Study

BACKGROUND

Severe haemolytic uraemic syndrome (HUS) in childhood can cause stroke, hemiplegia, cortical blindness, and psychomotor retardation. These outcomes are evident at the time of discharge immediately after the acute illness. Less is known about the neuropsychological outcomes of less severely affected children who recover from acute HUS.

AIMS

This multicentre case control study investigated the hypothesis that children who survive an acute episode of HUS without recognizable neurological injuries have greater impairment of cognitive, academic, and behavioural functions than controls.

DESIGN

Children with HUS were eligible if they had no evidence of severe neurological dysfunction when discharged from one of six Canadian hospitals. Controls had been admitted to hospital for a non-HUS illness and were matched by age, sex, first language, and socioeconomic status. All subjects underwent evaluation of behaviour, academic achievement, cognitive function, and verbal abilities using standardised tests administered by a psychometrist blinded to the case or control status.

RESULTS

Ninety-one case control pairs were enrolled. No important differences between patients with HUS and paired controls were evident on tests of IQ, behaviour, verbal abilities, or academic achievement. There was no increased risk of attention deficit disorder among patients with HUS. There was no correlation between the severity of acute renal failure and neuropsychological measures, although scores on some verbal ability tests were lower in those with the highest serum creatinine concentrations during illness.

CONCLUSIONS

Children discharged from hospital without apparent neurological injury after an episode of acute HUS do not have an increased risk of subclinical problems with learning, behaviour, or attention.

Hemolytic uremic syndrome in Belgium: incidence and association with verocytotoxin-producing Escherichia coli infection

OBJECTIVE: To evaluate the incidence of hemolytic uremic syndrome (HUS) in Belgium and to determine the role of verocytotoxin-producing Escherichia coli O157:H7 and other serotypes (non-O157 VTEC). METHODS: Twenty-two centers, including the seven university hospitals, registered prospectively all cases of HUS; they collected clinical samples for isolation of VTEC strains and serum for detection of specific O-lipopolysaccharide antibodies. RESULTS: Forty-seven cases of HUS (including five incomplete cases) were recorded. Three cases were seen in non-residents. The incidence of complete HUS in Belgian residents was 4.3 cases/100 000 in children <5 years old, 1.8 cases/100 000 when all children <15 years were considered, and 0.42/100 000 when patients of all ages were taken into account. By combining bacteriologic and serologic results, evidence of VTEC infection was obtained in 64% of the patients, mainly but not exclusively in children with prodromal diarrhea. The 13 VTEC isolates belonged to serotypes O157:H7 (nine isolates), O26:H11, O121:H---, O145:H--- and O172:H--- (one each) and all produced VT2 (+VT2vh-a in three O157 strains) and were positive for the eaeA gene. CONCLUSIONS: The incidence rate found in this study and the high mortality and morbidity linked with this syndrome warrant further registration of pediatric and post-diarrheic adult HUS cases and also examination of stools for both O157 and non-O157 VTEC strains. For effective prevention of this disease, further study of the serotypes and accessory virulence factors associated with HUS is needed.

Verotoxins inhibit the growth of and induce apoptosis in human astrocytoma cells

Verotoxin 1 (VT1) is an E. coli toxin comprising an A subunit with N-glycanase activity, and five smaller B subunits capable of binding to the functional receptor globotriaosylceramide (Galalpha1-4-Galbeta1-4-Glcceramide-Gb3). VT is implicated in hemorrhagic colitis and the more serious hemolytic uremic syndrome. VT1 is active against various tumor cell lines in vitro and in vivo. To extend the anti-cancer spectrum of activity of VT to human brain tumors, in the present analysis we studied the effects of VT on the growth of 6 permanent human astrocytoma cell lines. All astrocytoma cell lines analyzed express Gb3 and were sensitive to VT-1 at a dose of 50 ng/ml, but sensitivity was not proportional to the relative Gb3 concentration. VT induced apoptosis in these cells was shown by electron microscopy. Morphological evidence (nuclear shrinkage and chromatin condensation) of apoptosis could be clearly distinguished 1.5 hrs after toxin addition. Ultrastructural preservation of organelles was observed in conjunction with blebbing of the plasma membrane, condensation of chromatin within the nucleus and nuclear shrinkage. Apoptosis was also induced by the recombinant toxin B subunit alone, suggesting that the ligation of Gb3 is the primary induction mechanism. These studies indicate that verotoxin/Gb3 targetting may provide a novel basis for the inhibition of astrocytoma tumour cell growth.

Escherichia coli O157:H7

Escherichia coli O157 was first identified as a human pathogen in 1982. One of several Shiga toxin-producing serotypes known to cause human illness, the organism probably evolved through horizontal acquisition of genes for Shiga toxins and other virulence factors. E. coli O157 is found regularly in the faeces of healthy cattle, and is transmitted to humans through contaminated food, water, and direct contact with infected people or animals. Human infection is associated with a wide range of clinical illness, including asymptomatic shedding, non-bloody diarrhoea, haemorrhagic colitis, haemolytic uraemic syndrome, and death. Since laboratory practices vary, physicians need to know whether laboratories in their area routinely test for E. coli O157 in stool specimens. Treatment with antimicrobial agents remains controversial: some studies suggest that treatment may precipitate haemolytic uraemic syndrome, and other studies suggest no effect or even a protective effect. Physicians can help to prevent E. coli O157 infections by counselling patients about the hazards of consuming undercooked ground meat or unpasteurised milk products and juices, and about the importance of handwashing to prevent the spread of diarrhoeal illness, and by informing public-health authorities when they see unusual numbers of cases of bloody diarrhoea or haemolytic uraemic syndrome.

Inflammatory mediators in Escherichia coli O157:H7 hemorrhagic colitis and hemolytic-uremic syndrome

BACKGROUND

Recent experimental data suggest that the inflammatory response of the host to verotoxin and/or lipopolysaccharides of Escherichia coli is involved in the pathophysiology of verotoxin-producing E. coli (VTEC) infections.

METHODS

We measured the circulating concentrations of cytokines [TNF-alpha, interleukin (IL)-1-beta, IL-1 receptor antagonist (Ra), IL-6, IL-8, IL-10] and soluble leukocyte adhesion molecules (L-selectin, P-selectin, E-selectin, intracellular cell adhesion molecule-1, vascular cell adhesion molecule-1) by sandwich enzyme-linked immunosorbent assay among (1) normal controls (n = 12), (2) disease controls with hemorrhagic colitis (HC) not associated with VTEC infections (n = 57), (3) patients with uncomplicated HC caused by E. coli O157:H7 (n = 30), and (4) children with hemolytic-uremic syndrome (HUS) (n = 28). Patients with HUS were matched with children who presented an uncomplicated HC caused by E. coli O157:H7 for the time interval elapsed between the onset of HC and that of blood sample collection.

RESULTS

Concentrations of TNF-alpha and IL-1-beta were undetectable. Children with HUS were characterized by increased amounts of IL-6 and IL-8, lower values of soluble L-selectin as well as increased levels of IL-10 and IL-1Ra. The circulating concentrations of IL-1Ra were higher among children with O157:H7 HC who subsequently developed HUS.

CONCLUSIONS

Increased pro- and antiinflammatory cytokine responses are produced by the host during the development of HUS among children with VTEC infections. Further studies are needed to determine their relative contribution to the pathophysiology of classic HUS.

Risk of hemolytic uremic syndrome after sporadic Escherichia coli O157:H7 infection: results of a Canadian collaborative study. Investigators of the Canadian Pediatric Kidney Disease Research Center

OBJECTIVES

The objectives of this study were to better estimate the age-specific risks of hemolytic uremic syndrome (HUS) and hemolytic anemia after Escherichia coli O157:H7 infection among a representative cohort of both referred and nonreferred children with documented illness from the province of Alberta and to compare this with the rates in children evaluated at referral centers in the rest of Canada.

STUDY DESIGN

Children with HUS or E. coli O157:H7 gastroenteritis were eligible if they were < 15 years of age. Hemoglobin, blood smear, urinalysis, and serum creatinine were obtained 8 to 10 days after the onset of diarrhea to ascertain for hemolysis, anemia, thrombocytopenia, and renal injury. Subjects were monitored for 1 month.

RESULTS

From June 1991 to March 1994, HUS was diagnosed in 205 children. Of these 77% had evidence of E. coli O157:H7 infection. A further 582 children had E. coli O157:H7 gastroenteritis, of whom 18 had hemolytic anemia. The risk of HUS after E. coli O157:H7 infection in Alberta was 8.1% (95% confidence interval, 5.3 to 11.6) compared with 31.4% in referral centers in the rest of Canada. In Alberta the highest age-specific risk of HUS/hemolytic anemia was 12.9% in those < 5 years of age.

CONCLUSIONS

These data will help guide clinical care and provide a basis for estimating the sample sizes required in future treatment trials for the secondary prevention of HUS.

Genomic comparisons and Shiga toxin production among Escherichia coli O157:H7 isolates from a day care center outbreak and sporadic cases in southeastern Wisconsin

Contour-clamped homogeneous electric field pulsed-field gel electrophoresis (CHEF-PFGE) was used to compare Wisconsin isolates of Escherichia coli O157:H7, including 39 isolates from a 1994 day care center outbreak, 28 isolates from 18 individuals from the surrounding geographic area with sporadic cases occurring during the 3 months before the outbreak, and 3 isolates, collected in 1995, from patients with hemolytic-uremic syndrome (HUS) who were from eastern Wisconsin counties other than those inhabited by the day care center and sporadic-case individuals. The technique of CHEF-PFGE using XbaI identified seven highly related restriction endonuclease digestion profiles (REDPs) (93 to 98% similarity) among the 39 day care center isolates and nine XbaI REDPs (63 to 93% similarity) among the 28 isolates from sporadic-case individuals, including REDP 33, which was exhibited by both day care and sporadic-case isolates. PFGE analyses of sequential E. coli O157:H7 isolates from symptomatic day care center attendees revealed that the REDPs of 25 isolates from eight patients were indistinguishable whereas the REDPs of 2 of 6 isolates from two patients differed slightly (93 to 95% similarity). The REDPs of the three isolates from 1995 HUS patients were 78 to 83% similar, with REDP 26 being exhibited by one HUS-associated isolate and an isolate from one day care attendee who did not develop HUS. The genes for both Shiga toxins I and II (stx1 and stx2, respectively) were detected in all but one isolate (sporadic case), and Shiga toxin production by the day care center isolates was not significantly different from that of the other isolates, including the three HUS-associated isolates. Analyses of E. coli O157:H7 isolates from both the day care center outbreak and sporadic cases by CHEF-PFGE permitted us to define the REDP variability of an outbreak and geographic region and demonstrated that the day care center outbreak and a HUS case in 1995 were caused by E. coli O157:H7 strains endemic to eastern Wisconsin.

Binding ofEscherichia coliverotoxins to cell surface protein on wild-type and globotriaosylceramide-deficient Vero cells

We have examined verotoxin (VT) binding to cell surface proteins. When Vero or globotriaosylceramide (Gb3) deficient Vero (VRP) cells were incubated with125I-labelled verotoxin 2 (VT2) and disuccinimidyl suberate cross-linker, SDS-PAGE of cell lysates showed radiolabelled bands at 44, 50, 60, 86, 102, and 138 kDa. When125I-labelled verotoxin 1 (VT1) was cross-linked, radioactive bands occurred at 51, 67, 101, 160, 188, and 232 kDa. In contrast,125I-labelled VT1 B subunit produced a single radioactive band migrating at 50 kDa. CHO cells did not bind labelled VT. VT2 binding to VRP cells fit a rectangular hyperbola suggesting a single class of binding sites. In contrast, VT1 and VT1 B subunit binding to VRP cells was best fit by sigmoidal curves suggesting the presence of positive cooperativity between at least two binding sites. Scatchard analysis of VT2 binding data yielded 3.5 times 109molecules bound/ µg of cell protein with an equilibrium dissociation constant (KD) of 13 nM. The apparent KDwas 9.7 nM for VT1 and 73.2 nM for VT1 B subunit. These results indicate that VT binds to a protein, or proteins, on the surface of susceptible cells and that there appear to be differences between VT1 and VT2 binding. Interactions between VT1 or VT2 and the proteins demonstrated here may be important in the biological activity of VT.Key words: verotoxin, protein receptors, hemolytic uremic syndrome, Escherichia coli.

Localization of intravenously administered verocytotoxins (Shiga-like toxins) 1 and 2 in rabbits immunized with homologous and heterologous toxoids and toxin subunits

Rabbits challenged intravenously with Shiga toxin or with Escherichia coli verocytotoxin 1 or 2 (VT1 or VT2) are known to develop diarrhea, paralysis, and death, which can be prevented by immunization with a toxoid. The pathological effects of VT1 in the central nervous system and the gastrointestinal tract of unimmunized rabbits correlate with the localization of 125I-VT1 in these tissues, whereas in immunized animals, localization of 125I-VT1 in target tissues is inhibited and labeled toxin is cleared by the liver and spleen. By using the approach described above in this study, rabbits immunized with VT1 toxoid, VT2 toxoid, or with the A or B subunit of each toxin were challenged with intravenous 125I-VT1 or 125I-VT2. After 2 h, the animals were sacrificed, and selected tissues were analyzed for uptake of labeled toxin. It was found that animals immunized with either VT1 toxoid or VT2 toxoid were protected from target tissue uptake of both 125I-VT1 and 125I-VT2. Rabbits immunized with either the VT1 A or VT2 A subunit were also protected from target tissue uptake of both the homologous and heterologous 125I-labeled holotoxins. In contrast, in animals immunized with the toxin B subunits, protection extended only against challenge by the homologous toxin. These results provide evidence of VT1 and VT2 cross-neutralization in vivo in the rabbit model and indicate that the in vivo cross-neutralization is a function, mainly, of antibodies directed to the VT A subunits. This suggests that the VT1 A or VT2 A subunit may be a suitable immunogen for immunizing humans against systemic VT-mediated disease.

Predictors of hemolytic uremic syndrome in children during a large outbreak of Escherichia coli O157:H7 infections

OBJECTIVE

To evaluate risk factors for progression of Escherichia coli O157:H7 infection to the hemolytic uremic syndrome (HUS).

STUDY DESIGN

We conducted a retrospective cohort study among 278 Washington State children <16 years old who developed symptomatic culture-confirmed E coli O157:H7 infection during a large 1993 outbreak. The purpose of the study was to determine the relative risk (RR) of developing HUS according to demographic characteristics, symptoms, laboratory test results, and medication use in the first 3 days of illness.

RESULTS

Thirty-seven (14%) children developed HUS. In univariate analysis, no associations were observed between HUS risk and any demographic characteristic, the presence of bloody diarrhea or of fever, or medication use. In multivariate analysis, HUS risk was associated with, in the first 3 days of illness, use of antimotility agents (odds ratio [OR] = 2.9; 95% confidence interval [CI] 1.2-7.5) and, among children <5.5 years old, vomiting (OR = 4. 2; 95% CI 1.4-12.7). Among the 128 children tested, those whose white blood cell (WBC) count was >/=13 000/microL in the first 3 days of illness had a 7-fold increased risk of developing HUS (RR 7. 2; 95% CI 2.8-18.5). Thirteen (38%) of the 34 patients with a WBC count >/=13 000/microL developed HUS, but only 5 (5%) of the 94 children whose initial WBC count was <13 000/microL progressed to HUS. Among children who did not develop HUS, use of antimotility agents in the first 3 days of illness was associated with longer duration of bloody diarrhea.

CONCLUSIONS

Prospective studies are needed to further evaluate measures to prevent the progression of E coli O157:H7 infection to HUS and to assess further clinical and laboratory risk factors. These data argue against the use of antimotility agents in acute childhood diarrhea. Our finding that no intervention decreased HUS risk underscores the importance of preventing E coli O157:H7 infections.

Comparison of the western blot assay with the neutralizing-antibody and enzyme-linked immunosorbent assays for measuring antibody to verocytotoxin 1

A Western blot (immunoblot) assay (WBA) was developed to detect immunoglobulin G (IgG) antibodies against Escherichia coli Verocytotoxin 1 (VT1) by using a chemiluminescence detection system. The assay was compared with a VT1-neutralizing-antibody (VT1-NAb) assay and an anti-VT1 IgG enzyme-linked immunosorbent assay (ELISA). When four human serum samples that were known to be positive by VT1-NAb assay and ELISA were titrated to the endpoint by the three assays, the WBA gave endpoint titers that were up to 8-fold higher than those by ELISA and up to 256-fold higher than those by the VT1-NAb assay. Of 32 serum samples that were known to be positive by VT1-NAb assay and ELISA, 31 (97%) were positive by WBA; the one sample with a discrepant result gave borderline results by the VT1-NAb assay and ELISA. Of 52 serum samples that were known to be negative by the VT1-NAb assay and ELISA, 50 (96%) were negative and 2 (4%) were positive by WBA. Of 44 serum samples that gave discrepant results by the VT1-NAb assay and ELISA, neither of the latter correlated with the results of WBA. In an investigation of 19 pairs of acute- and convalescent-phase serum samples from patients with hemolytic-uremic syndrome, 10 pairs that were positive by the VT1-NAb assay were also WBA positive, while 9 pairs that were NAb negative were also WBA negative. The WBA is inherently more specific and sensitive than either the NAb assay or the ELISA and may be used as a "gold standard" to detect IgG antibodies to VT1. Like the NAb assay and the ELISA for detecting antibodies to VT1, the WBA has little to offer in the diagnostic setting but is expected to play an important role in seroepidemiological studies.

Haemolytic-uraemic syndrome in the Hunter: public health implications

Three cases of haemolytic-uraemic syndrome in the Hunter area were reported in February 1995. An investigation was initiated to identify any verocytotoxic Escherichia coli in clinical samples that could be associated with the development of the disease. Escherichia coli O6:H- and O2:H7 were isolated from Case 1. No organisms were identified for Case 2, and Case 3 samples yielded Campylobacter jejuni. In addition, efforts were made to trace sources of any such pathogens in food samples or in the environment generally. Shiga-like toxins were found in meat products sampled from butchers' shops patronised by the families of the three cases. However, it was not found possible to match stool samples with samples of food from sources used by the families of the children. Environmental factors seemed likely to have played a significant role in the development of haemolytic-uraemic syndrome in Case 3. It is suggested that the incidence of the disease may be reduced by increasing the frequency of testing of meat products for Shiga-like toxins I and II and through educational and research programs.

[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.

Diarrhea in young children associated with Escherichia coli non-O157 organisms that produce Shiga-like toxin

OBJECTIVE

To assess the clinical manifestations and incidence of infection associated with Shiga-like toxin-producing Escherichia coli (SLTEC).

STUDY DESIGN

Children with diarrhea within a defined geographic area during a 12-month period were examined for the presence of SLTEC in their stools by polymerase chain reaction with the use of primers that were complementary to sequences of Shiga-like toxins types I and II and to other virulence factors.

RESULTS

There were 13 SLTEC infections among 468 children with diarrhea. Besides Shiga-like toxin sequences, the virulence genes eae and EHEC-hly were found in 10 isolates; these isolates were categorized as enterohemorrhagic E. coli (EHEC). Only 2 of 13 isolates were of the O157 strain. All reported cases occurred in summer (June through September) with the exception of one case in April. The infections were sporadic, and the infected children lived in rural and urban areas. Three infections in children with disabilities were hospital acquired. The majority of children had watery diarrhea, two had bloody diarrhea, and one had mild hemolytic-uremic syndrome. The overall incidence of SLTEC infection was 12.5 hospitalized children per 100,000 children less than 16 years of age.

CONCLUSIONS

The most frequent clinical manifestation of SLTEC infection was watery diarrhea indistinguishable from other forms of infectious diarrhea. The shift from the O157 strain toward non-O157 SLTEC strains associated with diarrhea, also observed in German patients with hemolytic-uremic syndrome, points to a change in the epidemiologic features of SLTEC-associated disease. Testing for non-O157 SLTEC should be considered in children with diarrhea without a recognized cause.

Screening for Escherichia coli O157:H7--a nationwide survey of clinical laboratories

The Association of State and Territorial Public Health Laboratory Directors has recommended that clinical laboratories screen at least all bloody stools for Escherichia coli O157:H7. We contacted the microbiology supervisors of 230 randomly selected clinical laboratories in the United States and administered a standardized questionnaire regarding stool culture practices. Of the 129 laboratories that performed stool cultures, only 70 (54%) reported screening either all stools or all bloody stools submitted for culture for E. coli O157:H7.

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.

Incomplete hemolytic-uremic syndrome in Argentinean children with bloody diarrhea

Argentina has an exceptionally high frequency of hemolytic-uremic syndrome (HUS). We sought to define prospectively the role of verocytotoxins (Shiga-like toxins [SLTs]) in 254 Argentinean children with grossly bloody diarrhea during spring and summer. Free fecal SLTs (I/II) and/or DNA probe-positive isolates were found in 99 (39%) of the children. During the follow-up period, HUS developed in 6 patients (4 with evidence of recent SLT infection based on stool studies); another 14 patients had some, but not all, of the abnormalities seen in typical HUS. The development of HUS or incomplete HUS in these children was significantly associated with recent SLT-Escherichia coli infection (p = 0.024). The high incidence of SLT-associated bloody diarrhea in Argentina explains, at least partially, the unusually high frequency of HUS. Our data indicate that incomplete forms of HUS may be common in patients with SLT-associated bloody diarrhea.

The bacterial colicin active against tumor cells in vitro and in vivo is verotoxin 1

We have identified verotoxin 1 (VT1) as the active component within an antineoplastic bacteriocin preparation from Escherichia coli HSC10 studied over two decades. Recombinant VT1 can simulate the toxicity of anticancer proteins (ACP), and the antineoplastic activity of ACP (and VT1) was abrogated by treatment with anti-VT1 antibody. Similarly, VT1 mimics the protective effect of ACP in a murine metastatic fibrosarcoma model. Prior immunization with VT1 B subunit prevents the effect of VT1 or ACP in this model. The activity of ACP against a variety of human ovarian cell lines was mimicked by VT1, and multidrug-resistant variants were significantly hypersensitive. Primary ovarian tumors and metastases contain elevated levels of globotriaosylceramide compared with normal ovaries, and overlay of frozen tumor sections showed selective VT binding to tumor tissue and the lumen of invading blood vessels. Our contention that VT1 could provide an additional approach to the management of certain human neoplasms is discussed.

Impact of free verotoxin testing on epidemiology of diarrhea caused by verotoxin-producing Escherichia coli

During a 10-week period in the summer of 1990, an epidemiologic investigation of the prevalence of verotoxin (VT)-producing Escherichia coli infection was conducted in Calgary, Alberta, Canada. Consecutive stool specimens (n = 3,577) were cultured for E. coli O157:H7, and fecal filtrates were tested for free VTs (FVTs). E. coli O157:H7 was recovered from 22 specimens (0.6%), but VT was detected in 74 specimens (2.1%). Sixty-nine stool specimens positive for FVTs or E. coli O157:H7 were probed for VT genes by colony blot hybridization; 22 of 38 VT gene probe-positive isolates were non-O157:H7 E. coli organisms. Fourteen of 22 strains could not be induced to produce VT in vitro, despite the presence of FVTs in the stool sample, positivity on colony blot hybridization, positive PCR probes with the primers described by Pollard et al. (D. R. Pollard, W. M. Johnson, H. Lior, S. D. Tyler, and K. R. Rozee, J. Clin. Microbiol. 28:540-545, 1990) or Gannon et al. (V. P. Gannon, R. K. King, J. Y. Kim, and E. J. Golsteyn-Thomas, Appl. Environ. Microbiol. 58:3809-3815, 1992) (but not those described by Karch and Meyer [H. Karch and T. Meyer, J. Clin. Microbiol. 27:2751-2757, 1989]), and positive Southern blot analysis of isolates in 10 of 14 strains. The patient survey questionnaire showed that E. coli O157:H7 infection was associated with bloody diarrhea of short duration, whereas infection with other serotypes or persistence of FVT only was associated with longer-duration nonbloody diarrheal illness. We conclude that (i) detection of FVT in stools enhances the diagnosis of VT infection threefold over cultures for E. coli O157:H7, (ii) cultures for E.coli O157:H7 detect the majority of organisms of that serotype, (iii) the spectrum of disease produced by organisms of non-O157:H7 serotypes may include less severe but more protracted illness, and (iv) differences in the in vivo and in vitro expression of toxin and results of genetic probe studies highlight the need to examine control mechanisms of toxin production.

Hemolytic uremic syndrome - clinical aspects and outcome of an outbreak: Report of 28 cases

Hemolytic uremic syndrome (HUS) is characterized by microangiopathic hemolytic anemia, thrombocytopenia and acute renal failure. There are two main subgroups: the typical form of HUS follows a diarrheal prodrome (D+HUS) and the atypical form is without the diarrheal prodrome (D-HUS). We have studied 28 children with HUS over a period of 15 months between 1992 and 1993. The median age was 2.2 years (range from six months to six years). All children had prodromal diarrhea. Hypertension was present in 71% and neurological complications in 39%. All the patients had oliguria or anuria (16 oliguric and 12 anuric). The mean duration of anuria was 16 days (range seven to 42 days). Serum creatinine on admission ranged between 112 and 1064 Amicromol/L (mean 453 Amicromol/L). The lowest hemoglobin level and platelet count during hospitalization ranged between 38 and 87 g/L and 7 to 147x109/L respectively. Leukocytosis on admission was present in 22 patients, low C3 was documented in 11 patients (34%), and four patients had low C4. All patients received fresh frozen plasma transfusion, a total of 25 patients received dialysis therapy, 19 patients were treated with peritoneal dialysis (PD), one patient had hemodialysis (HD), and five patients had both HD and PD. The mean duration of dialysis was 18 days (range three to 56 days). Only one patient died (mortality rate 3%). The median duration of hospital stay was 28 days (range eight to 90 days). We conclude that HUS is emerging as an important clinical and public health problem and that early comprehensive management including dialysis therapy, aggressive management of hypertension, fresh frozen plasma transfusion, and nutritional support all improve the outcome and decrease the mortality and morbidity in patients with HUS.

Lessons learned in the management of hemolytic uremic syndrome in children

Escherichia coli O.157:H7 is a serious and common human pathogen that can cause diarrhea, hemorrhagic colitis, and the hemolytic uremic syndrome (HUS). During a massive outbreak of infection with E coli O157:H7 in January 1993 in Washington State, more than 600 people, mostly children, acquired symptomatic infection, and 37 were hospitalized with HUS at Children's Hospital and Medical Center in Seattle, and six at other hospitals in Washington. Twenty-one (57%) required dialysis. Nineteen (51%) had significant extrarenal pathology: gastrointestinal in 14 patients (38%), cardiovascular in 13 (35%), pulmonary in 9 (24%), and neurological in 6 (16%). Most patients were managed nonoperatively, but three required total abdominal colectomy and one a left colectomy. No child had perforation. Three patients died, all of whom had multisystem disease. The authors recommend (1) that all patients with bloody diarrhea undergo microbiological evaluation for E coli O157:H7 before any surgical intervention; (2) avoidance of antibiotics and antimotility agents in patients with proven or suspected infection with E coli O157:H7 until the safety and efficacy of such interventions have been established in controlled trials; (3) that patients with E coli O157:H7 infections be evaluated for microangiopathic changes consistent with HUS in the week after onset of diarrhea; (4) nasogastric suction for severe symptoms, and frequent abdominal evaluations, tests (electrolytes/amylase), and roentgenograms to exclude treatable abdominal disorders; and (5) institution of hemodialysis for oliguria/anuria, acidosis, or rising creatinine. The authors recommend surgical exploration for toxic megacolon, colonic perforation, acidosis unresponsive to dialysis, or recurrent signs of obstruction or colonic stricture.

Myocarditis and haemolytic uraemic syndrome

A 13 year old girl is reported who presented with haemolytic uraemic syndrome (HUS) due to Escherichia coli O157:H7 infection. She died during the acute phase of the illness after an episode of unexplained sudden circulatory collapse. Postmortem examination confirmed the diagnosis of HUS and showed histological evidence of myocarditis manifested by the presence of inflammatory cell infiltration in the myocardium and around the conducting system.