Post-diarrheal Hemolytic Uremic Syndrome Research Articles

Progression of renal damage and tubular regeneration in pregnant and non-pregnant adult female rats inoculated with a sublethal dose of Shiga toxin 2

BackgroundShiga toxin-producing Escherichia coli is the main cause of post-diarrheal hemolytic uremic syndrome (HUS) which produces acute kidney injury mainly in children, although it can also affect adults. The kidneys are the organs most affected by Shiga toxin type 2 (Stx2) in patients with HUS. However, previous studies in pregnant rats showed that a sublethal dose of Stx2 causes severe damage in the uteroplacental unit and induces abortion, whereas produces mild to moderate renal damage. The aim of the present work was to study the progression of renal injury caused by a sublethal dose of Stx2, as well as renal recovery, in pregnant and non-pregnant rats, and to investigate whether pregnancy physiology may affect renal damage progression mediated by Stx2. MethodsRenal function and histopathology was evaluated in pregnant rats intraperitoneally injected with a sublethal dose of Stx2 (0.5 ng/g bwt) at the early stage of gestation (day 8 of gestation), and results in these rats were compared over time with those observed in non-pregnant female rats injected with the same Stx2 dose. Hence, progression of cell proliferation and dedifferentiation in renal tubular epithelia was also investigated. ResultsThe sublethal dose of Stx2 induced abortion in pregnant rats as well as a significant more extended functional and histological renal injury in non-pregnant rats than in pregnant rats. Stx2 also caused decreased ability to concentrate urine in non-pregnant rats compared to their controls. However, renal water handling in pregnant rats was not altered by Stx2, and was significantly different than in non-pregnant rats. The greatest renal injury in both pregnant and non-pregnant rats was observed at 4 days post-Stx2 injection, and coincided with a significant increase in tubular epithelial proliferation. Expression of mesenchymal marker vimentin in tubular epithelia was consistent with the level of tubular damage, being higher in non-pregnant rats than in pregnant rats. Recovery from Stx2-induced kidney injury was faster in pregnant rats than in non-pregnant rats. ConclusionsAdaptive mechanisms developed during pregnancy such as changes in water handle and renal hemodynamic may contribute to lessen the Stx2-induced renal injury, perhaps at the expense of fetal loss.

Etiological diagnosis of post-diarrheal hemolytic uremic syndrome (HUS): humoral response contribution.

Hemolytic uremic syndrome (HUS) is characterized by microangiopathic hemolysis, thrombocytopenia, and thrombus formation leading to tissue injury. HUS is classified according to its etiology as post-diarrheal or atypical HUS. Differential diagnosis of both entities continues to be a challenge for pediatric physicians. The aim was to improve the rapid etiological diagnosis of post-diarrheal HUS cases based on the detection of Shiga toxin (Stx)-producing Escherichia coli (STEC) infection by screening of stx1/stx2 and rfbO157 in cultured stools by multiplex PCR, and the additional detection of anti-lipopolysaccharide (anti-LPS) O157, O145, and O121 antibodies by Glyco-iELISA test. In addition, we studied patients' relatives to detect circulating pathogenic strains that could contribute to HUS diagnosis and/or lead to the implementation of measures to prevent dissemination of familial outbreaks. This study describes the diagnosis of 31 HUS patients admitted to Hospital Municipal de Niños Prof Dr Ramón Exeni during the 2017-2020 period. Stool PCR confirmed the diagnosis of STEC associated with HUS in 38.7% of patients (12/31), while anti-LPS serology did in 88.9% (24/27). In those patients in which both methods were carried out (n = 27), a strong association between the results obtained was found. We found that 30.4% of HUS patients had at least one relative positive for STEC. We could identify 96.3% (26/27) of HUS cases as secondary to STEC infections when both methods (genotyping and serology) were used. The results demonstrated a high circulation of STEC in HUS families and the prevalence of the STEC O157 serotype (83%) in our pediatric cohort. A higher-resolution version of the Graphical abstract is available as Supplementary information.

Shiga Toxin 2 Triggers C3a-Dependent Glomerular and Tubular Injury through Mitochondrial Dysfunction in Hemolytic Uremic Syndrome.

Shiga toxin (Stx)-producing Escherichia coli is the predominant offending agent of post-diarrheal hemolytic uremic syndrome (HUS), a rare disorder of microvascular thrombosis and acute kidney injury possibly leading to long-term renal sequelae. We previously showed that C3a has a critical role in the development of glomerular damage in experimental HUS. Based on the evidence that activation of C3a/C3a receptor (C3aR) signaling induces mitochondrial dysregulation and cell injury, here we investigated whether C3a caused podocyte and tubular injury through induction of mitochondrial dysfunction in a mouse model of HUS. Mice coinjected with Stx2/LPS exhibited glomerular podocyte and tubular C3 deposits and C3aR overexpression associated with cell damage, which were limited by C3aR antagonist treatment. C3a promoted renal injury by affecting mitochondrial wellness as demonstrated by data showing that C3aR blockade reduced mitochondrial ultrastructural abnormalities and preserved mitochondrial mass and energy production. In cultured podocytes and tubular cells, C3a caused altered mitochondrial fragmentation and distribution, and reduced anti-oxidant SOD2 activity. Stx2 potentiated the responsiveness of renal cells to the detrimental effects of C3a through increased C3aR protein expression. These results indicate that C3aR may represent a novel target in Stx-associated HUS for the preservation of renal cell integrity through the maintenance of mitochondrial function.

Eliglustat prevents Shiga toxin 2 cytotoxic effects in human renal tubular epithelial cells.

Shiga toxin-producing Escherichia coli is responsible for post-diarrheal (D+) hemolytic uremic syndrome (HUS), which is a cause of acute renal failure in children. The glycolipid globotriaosylceramide (Gb3) is the main receptor for Shiga toxin (Stx) in kidney target cells. Eliglustat (EG) is a specific and potent inhibitor of glucosylceramide synthase, first step of glycosphingolipid biosynthesis, actually used for the treatment of Gaucher's disease. The aim of the present work was to evaluate the efficiency of EG in preventing the damage caused by Stx2 in human renal epithelial cells. Human renal tubular epithelial cell (HRTEC) primary cultures were pre-treated with different dilutions of EG followed by co-incubation with EG and Stx2 at different times, and cell viability, proliferation, apoptosis, tubulogenesis, and Gb3 expression were assessed. In HRTEC, pre-treatments with 50 nmol/L EG for 24 h, or 500 nmol/L EG for 6 h, reduced Gb3 expression and totally prevented the effects of Stx2 on cell viability, proliferation, and apoptosis. EG treatment also allowed the development of tubulogenesis in 3D-HRTEC exposed to Stx2. EG could be a potential therapeutic drug for the prevention of acute kidney injury caused by Stx2. For the first time, we have demonstrated that Eliglustat prevents Shiga toxin 2 cytotoxic effects on human renal epithelia, by reducing the expression of the toxin receptor globotriaosylceramide. The present work also shows that Eliglustat prevents Shiga toxin 2 effects on tubulogenesis of renal epithelial cells. Eliglustat, actually used for the treatment of patients with Gaucher's disease, could be a therapeutic strategy to prevent the renal damage caused by Shiga toxin.

Development and Evaluation of a Novel VHH-Based Immunocapture Assay for High-Sensitivity Detection of Shiga Toxin Type 2 (Stx2) in Stool Samples.

Shiga toxin (Stx)-producing Escherichia coli (STEC) is the main cause of postdiarrheal hemolytic-uremic syndrome (HUS), a life-threatening clinical complication characterized by hemolytic anemia, thrombocytopenia, and acute renal failure that mainly affects children. A relevant feature of STEC strains is the production of Stx, and all of them express Stx1 and/or Stx2 regardless of the strain serotype. Therefore, Stx detection assays are considered the most suitable methods for the early detection of STEC infections. Single-domain antibodies from camelids (VHHs) exhibit several advantages in comparison with conventional antibodies, making them promising tools for diagnosis. In this work, we have exploited VHH technology for the development of an immunocapture assay for Stx2 detection. Thirteen anti-Stx2 VHHs previously obtained from a variable-domain repertoire library were selected and evaluated in 130 capture-detection pair combinations for Stx detection. Based on this analysis, two VHHs were selected and a double VHH-based biotin-streptavidin capture enzyme-linked immunosorbent assay (ELISA) with spectrophotometric detection was developed and optimized for Stx2 detection. This assay showed an excellent analytical and clinical sensitivity in both STEC culture supernatants and stool samples even higher than the sensitivity of a commercial ELISA. Furthermore, based on the analysis of stool samples, the VHH-based ELISA showed high correlation with stx2 detection by PCR and a commercial rapid membrane-based immunoassay. The intrinsic properties of VHHs (high target affinity and specificity, stability, and ease of expression at high yields in recombinant bacteria) and their optimal performance for Stx detection make them attractive tools for the diagnosis of HUS related to STEC (STEC-HUS).

Postdiarrheal hemolytic uremic syndrome in Egyptian children: An 11-year single-center experience.

Hemolytic-uremic syndrome (HUS) is a leading cause of childhood acute kidney injury (AKI) worldwide, with its postdiarrheal (D+HUS) form being the most common. Scarce data are available regarding D+HUS epidemiology from developing countries. This study aims to reveal the characterization of D+ HUS in Egyptian children. This is a retrospective study of all children with D+HUS admitted to a tertiary pediatric hospital in Egypt between 2007 and 2017. The study included epidemiological, clinical and laboratory data; management details; and outcomes. A cohort of 132 children aged 4months to 12 years was analyzed. Yearly incidence peaked in 2017, and spring showed the highest peak. All cases had a diarrheal prodrome that was bloody in 83% of the cases. Edema and decreased urine output were the most frequent presentations (50.3% and 42.4%, respectively). Escherichia coli was detected in 56 cases. Dialysis was performed in 102 cases. Eight patients died during acute illness, while five patients experienced long-term sequels. Lactate dehydrogenase (LDH) positively correlated with serum creatinine and negatively correlated with reticulocytic count. Univariate analysis showed that longer anuria duration, short duration between diarrheal illness and development of AKI (P = 0.001), leukocyte count above 20 × 109 cells/L (P ≤ 0.001), platelet count below 30 × 109 cells/L (P = 0.02), high LDH levels (P = 0.02) and hematocrit above 30% (P = 0.0001), need for dialysis (P = 0.03), and neurological involvement (P ≤ 0.001) were associated with unfavorable outcomes. This is the first report with a detailed insight into the epidemiology of D+HUS in Egyptian children. The incidence of D+HUS is increasing in our country due to increased awareness of the disease and the poor public health measures. Anuria duration, leukocyte count, and neurological involvement are predictors of poor outcome in the current work, and LDH is introduced as a marker of disease severity.

Complement Gene Variants and Shiga Toxin-Producing Escherichia coli-Associated Hemolytic Uremic Syndrome: Retrospective Genetic and Clinical Study.

Inherited complement hyperactivation is critical for the pathogenesis of atypical hemolytic uremic syndrome (HUS) but undetermined in postdiarrheal HUS. Our aim was to investigate complement activation and variants of complement genes, and their association with disease severity in children with Shiga toxin-associated HUS. Determination of complement biomarkers levels and next-generation sequencing for the six susceptibility genes for atypical HUS were performed in 108 children with a clinical diagnosis of post-diarrheal HUS (75 Shiga toxin-positive, and 33 Shiga toxin-negative) and 80 French controls. As an independent control cohort, we analyzed the genotypes in 503 European individuals from the 1000 Genomes Project. During the acute phase of HUS, plasma levels of C3 and sC5b-9 were increased, and half of patients had decreased membrane cofactor protein expression, which normalized after 2 weeks. Variants with minor allele frequency <1% were identified in 12 Shiga toxin-positive patients with HUS (12 out of 75, 16%), including pathogenic variants in four (four out of 75, 5%), with no significant differences compared with Shiga toxin-negative patients with HUS and controls. Pathogenic variants with minor allele frequency <0.1% were found in three Shiga toxin-positive patients with HUS (three out of 75, 4%) versus only four European controls (four out of 503, 0.8%) (odds ratio, 5.2; 95% confidence interval, 1.1 to 24; P=0.03). The genetic background did not significantly affect dialysis requirement, neurologic manifestations, and sC5b-9 level during the acute phase, and incident CKD during follow-up. However, the only patient who progressed to ESKD within 3 years carried a factor H pathogenic variant. Rare variants and complement activation biomarkers were not associated with severity of Shiga toxin-associated HUS. Only pathogenic variants with minor allele frequency <0.1% are more frequent in Shiga toxin-positive patients with HUS than in controls.

Complement Activation Contributes to the Pathophysiology of Shiga Toxin-Associated Hemolytic Uremic Syndrome.

Shiga toxin (Stx)-producing Escherichia coli (STEC) infections have become a threat to public health globally because of the severe illnesses that they can trigger, such as hemorrhagic colitis and the post-diarrheal hemolytic uremic syndrome (HUS), characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney failure. Glomerular endothelial cells are primary targets of Stx which, after binding to its specific receptor globotriaosylceramide, upregulates proinflammatory proteins involved both in the recruitment and adhesion of leukocytes and thrombus formation at the site of endothelial injury. In this review, we discuss the role of complement activation in promoting glomerular microvascular dysfunction, providing evidence from experimental models and patients with STEC-HUS. Within the glomerulus, an important target for Stx-induced complement activation is the podocyte, a cell type that is in close contact with endothelial cells and participates in maintaining the filtration barrier. Recently, podocyte injury and loss have been indicated as potential risk factors for long-term renal sequelae in patients with STEC-HUS. Therapeutic approaches targeting the complement system, that may be useful options for patients with STEC-HUS, will also be discussed.

Case definitions of hemolytic uremic syndrome following Escherichia coli O157:H7 infection vary in validity

BackgroundMultiple case definitions for post-diarrheal hemolytic uremic syndrome (D+ HUS) associated with Shiga toxin-producing Escherichia coli (STEC) are used across public health, research, and clinical practice. MethodsTo identify a single definition of D+ HUS for standardized use, we evaluated the comparability and validity of four common, heterogeneous definitions: the Council of State and Territorial Epidemiologists (CSTE) definition, hematology-focused and age-focused definitions from the literature, and hospital diagnosis. We reviewed medical records from 471 hospitalized E. coli O157:H7 cases reported in Washington State, 2005–2014. We assessed 1) reliability across definitions, 2) comparability of temporal trends, and 3) sensitivity and specificity using an omnibus reference standard, developed using a combination of definition agreement and clinical outcomes. With the standard, we classified cases as definite, borderline, or unlikely/not post-diarrheal D+ HUS. ResultsReliability was highest between the age-focused definition and hospital diagnosis (κ = 0.84), and temporal trends were largely comparable across definitions. For definite D+ HUS cases, the age-focused definition had the highest overall validity [100% sensitivity, 95% confidence interval (CI): 94%, 100%; 96% specificity, 95% CI: 94%, 98%]. The CSTE definition had low specificity (75%, 95% CI: 70%, 79%). ConclusionsIn this review, the CSTE definition overestimated the burden of D+ HUS, and the age-focused definition provided the best overall reliability and validity to define post-diarrheal D+ HUS. Disease monitoring and research activities should consider using the age-focused D+ HUS definition.

Postdiarrheal hemolytic and uremic syndrome with severe multiorgan involvement and associated early risk factors

AimIdentifying early clinical and biological factors associated with severe forms of postdiarrheal hemolytic uremic syndrome (D+HUS) that may help practitioners determine appropriate treatment. MethodsThis retrospective study was conducted in 49 children with D+HUS between 2001 and 2011. Severe forms were defined as occurrence of one of the following conditions: death, major neurological involvement, cardiovascular involvement, and/or the presence of sequelae (neurological, cardiovascular, pancreatic, or renal). ResultsDuring the acute phase, 35 children exhibited at least one type of extrarenal involvement including 13 severe forms with a median delayed occurrence after admission of 4.5 days (range: 1–8) for comatose children and 5 days (range: 2–6) for cardiovascular involvement; 32 children required dialysis and three died. In multivariate analysis, (i) major neurological involvement (n=13), (ii) dialysis (n=32), and (iii) sequelae (n=12) were associated with (i) fever during the prodromal phase requiring dialysis at admission, (ii) C-reactive protein level (CRP) >22mg/L at admission, and (iii) major neurological involvement and a white blood cell count (WBC)>20×103/mm3 during the acute stage, respectively. ConclusionsD+HUS is a multiorgan disease with a delayed occurrence of life-threatening extrarenal organ involvement. Severe forms appear to be associated with early biological and clinical inflammatory parameters.

Genetic Susceptibility to Postdiarrheal Hemolytic-Uremic Syndrome After Shiga Toxin-Producing Escherichia coli Infection: A Centers for Disease Control and Prevention FoodNet Study.

Postdiarrheal hemolytic-uremic syndrome (D+HUS) following Shiga toxin-producing Escherichia coli (STEC) infection is a serious condition lacking specific treatment. Host immune dysregulation and genetic susceptibility to complement hyperactivation are implicated in non-STEC-related HUS. However, genetic susceptibility to D+HUS remains largely uncharacterized. Patients with culture-confirmed STEC diarrhea, identified through the Centers for Disease Control and Prevention FoodNet surveillance system (2007-2012), were serotyped and classified by laboratory and/or clinical criteria as having suspected, probable, or confirmed D+HUS or as controls and underwent genotyping at 200 loci linked to nondiarrheal HUS or similar pathologies. Genetic associations with D+HUS were explored by multivariable regression, with adjustment for known risk factors. Of 641 enrollees with STEC O157:H7, 80 had suspected D+HUS (41 with probable and 32 with confirmed D+HUS). Twelve genes related to cytokine signaling, complement pathways, platelet function, pathogen recognition, iron transport, and endothelial function were associated with D+HUS in multivariable-adjusted analyses (P ≤ .05). Of 12 significant single-nucleotide polymorphisms (SNPs), 5 were associated with all levels of D+HUS (intergenic SNP rs10874639, TFRC rs3804141, EDN1 rs5370, GP1BA rs121908064, and B2M rs16966334), and 7 SNPs (6 non-complement related) were associated with confirmed D+HUS (all P < .05). Polymorphisms in many non-complement-related genes may contribute to D+HUS susceptibility. These results require replication, but they suggest novel therapeutic targets in patients with D+HUS.

Прогнозирование риска развития неблагоприятных исходов постдиарейного гемолитико-уремического синдрома у детей

Прогнозирование риска развития неблагоприятных исходов постдиарейного гемолитико-уремического синдрома у детей

Effects of shiga toxin 2 on cellular regeneration mechanisms in primary and three-dimensional cultures of human renal tubular epithelial cells

Shiga toxin (Stx)-producing Escherichia coli (STEC) causes post-diarrheal Hemolytic Uremic Syndrome (HUS), which is one of the most common causes of acute renal failure in children in Argentine. The aim of the present work was to study the effects of Shiga toxin type 2 (Stx2) on regenerative mechanisms of primary cultures of human cortical renal tubular epithelial cells (HRTEC) and three-dimensional (3D) cultures of HRTEC. Primary cultures of HRTEC were able to develop tubular structures when grown in matrigel, which showed epithelial cells surrounding a central lumen resembling the original renal tubules. Exposure to Stx2 inhibited tubulogenesis in 3D-HRTEC cultures. Moreover, a significant increase in apoptosis, and decrease in cell proliferation was observed in tubular structures of 3D-HRTEC exposed to Stx2. A significant reduction in cell migration and vimentin expression levels was observed in HRTEC primary cultures exposed to Stx2, demonstrating that the holotoxin affected HRTEC dedifferentiation. Furthermore, a decreased number of cells expressing CD133 progenitor marker was found in HRTEC cultures treated with Stx2. The CD133 positive cells also expressed the Stx receptor globotriaosylceramide, which may explain their sensitivity to Stx2. In conclusion, Stx2 affects the regenerative processes of human renal tubular epithelial cells in vitro, by inhibiting cell dedifferentiation mechanisms, as well as tubules restoration. The development of 3D-HRTEC cultures that resemble original human renal proximal tubules is a novel in vitro model to study renal epithelial repair mechanisms after injury.

Comparative Characterization of Shiga Toxin Type 2 and Subtilase Cytotoxin Effects on Human Renal Epithelial and Endothelial Cells Grown in Monolayer and Bilayer Conditions.

Postdiarrheal hemolytic uremic syndrome (HUS) affects children under 5 years old and is responsible for the development of acute and chronic renal failure, particularly in Argentina. This pathology is a complication of Shiga toxin (Stx)-producing Escherichia coli infection and renal damage is attributed to Stx types 1 and 2 (Stx1, Stx2) produced by Escherichia coli O157:H7 and many other STEC serotypes. It has been reported the production of Subtilase cytotoxin (SubAB) by non-O157 STEC isolated from cases of childhood diarrhea. Therefore, it is proposed that SubAB may contribute to HUS pathogenesis. The human kidney is the most affected organ because very Stx-sensitive cells express high amounts of biologically active receptor. In this study, we investigated the effects of Stx2 and SubAB on primary cultures of human glomerular endothelial cells (HGEC) and on a human tubular epithelial cell line (HK-2) in monoculture and coculture conditions. We have established the coculture as a human renal proximal tubule model to study water absorption and cytotoxicity in the presence of Stx2 and SubAB. We obtained and characterized cocultures of HGEC and HK-2. Under basal conditions, HGEC monolayers exhibited the lowest electrical resistance (TEER) and the highest water permeability, while the HGEC/HK-2 bilayers showed the highest TEER and the lowest water permeability. In addition, at times as short as 20–30 minutes, Stx2 and SubAB caused the inhibition of water absorption across HK-2 and HGEC monolayers and this effect was not related to a decrease in cell viability. However, toxins did not have inhibitory effects on water movement across HGEC/HK-2 bilayers. After 72 h, Stx2 inhibited the cell viability of HGEC and HK-2 monolayers, but these effects were attenuated in HGEC/HK-2 bilayers. On the other hand, SubAB cytotoxicity shows a tendency to be attenuated by the bilayers. Our data provide evidence about the different effects of these toxins on the bilayers respect to the monolayers. This in vitro model of communication between human renal microvascular endothelial cells and human proximal tubular epithelial cells is a representative model of the human proximal tubule to study the effects of Stx2 and SubAB related to the development of HUS.

Postdiarrheal Hemolytic Uremic Syndrome in United States Children: Clinical Spectrum and Predictors of In-Hospital Death

To assess the clinical spectrum of postdiarrheal hemolytic uremic syndrome (D(+)HUS) hospitalizations and sought predictors of in-hospital death to help identify children at risk of poor outcomes. We assessed clinical variables collected through population-based surveillance of D(+)HUS in children <18 years old hospitalized in 10 states during 1997-2012 as predictors of in-hospital death by using tree modeling. We identified 770 cases. Of children with information available, 56.5% (430 of 761) required dialysis, 92.6% (698 of 754) required a transfusion, and 2.9% (22 of 770) died; few had a persistent dialysis requirement (52 [7.3%] of 716) at discharge. The tree model partitioned children into 5 groups on the basis of 3 predictors (highest leukocyte count and lowest hematocrit value during the 7 days before to 3 days after the diagnosis of hemolytic uremic syndrome, and presence of respiratory tract infection [RTI] within 3 weeks before diagnosis). Patients with greater leukocyte or hematocrit values or a recent RTI had a greater probability of in-hospital death. The largest group identified (n = 533) had none of these factors and had the lowest odds of death. Many children with RTI had recent antibiotic treatment for nondiarrheal indications. Most children with D(+)HUS have good hospitalization outcomes. Our findings support previous reports of increased leukocyte count and hematocrit as predictors of death. Recent RTI could be an additional predictor, or a marker of other factors such as antibiotic exposure, that may warrant further study.

Early erythropoietin in post-diarrheal hemolytic uremic syndrome: a case-control study.

Although erythropoietin (EPO) deficiency has been reported in children with post-diarrheal hemolytic uremic syndrome (D + HUS), very limited clinical data on EPO use in this disease are currently available. In this case-control study we examined whether EPO administration would reduce the number of red blood cell (RBC) transfusions in D + HUS patients under our care. Data from children treated exclusively with RBC transfusions (controls; n = 21) were retrospectively compared with data on those who also received EPO for the treatment of anemia (cases; n = 21). Both patient groups were similar in age (p = 0.9), gender (p = 0.12), weight (p = 1.00) and height (p = 0.66). Acute phase severity was also comparable, as inferred by the need for dialysis (p = 0.74), the duration of dialysis (p = 0.3), length of hospitalization (p = 0.81), presence of severe bowel (p = 1.00) or neurological injury (p = 0.69), arterial hypertension (p = 1.00) and death (p = 1.00). No differences in the hemoglobin level at admission (p = 0.51) and discharge (p = 0.28) were noted. Three children treated with EPO and two controls did not require any RBC transfusion (p = 1.00). Median number of RBC transfusions needed by cases and controls was 2 (p = 0.52). Treatment with EPO did not reduce the number of RBC transfusions in D + HUS children. Assessment of EPO efficacy in D + HUS merits further studies.

Laboratory predictors of acute dialysis in hemolytic uremic syndrome

Strict guidelines on use of dialysis in children with post-diarrheal hemolytic uremic syndrome (D + HUS) are lacking. This study investigated laboratory predictors of acute dialysis because they are more objective than clinical features. Added to this, given that urine output is also an objective parameter, its ability to predict dialysis requirements was also investigated. Out of 153 D + HUS children reviewed, 88 received dialysis and 65 did not. Initial laboratory parameters and diuresis between both groups were analyzed. Dialyzed patients had higher creatinine, urea, alanine aminotransferase, hematocrit and leukocyte count; and lower sodium, bicarbonate, and pH compared to non-dialyzed ones. Serum creatinine was the only independent predictor (P = 0.003) of dialysis; therefore, its ability to predict dialysis was estimated on receiver operating characteristic (ROC) curve analysis and using the Acute Kidney Injury Network (AKIN) staging system. Area under the ROC curve was 0.92 (95% confidence interval [95%CI]: 0.83-1) with a creatinine cut-off of 1.25 mg/dL (sensitivity, 100%; specificity, 76.5%) for children <1 year, and 0.93 (95%CI: 0.88-0.98) with a threshold of 2 mg/dL (sensitivity, 91%; specificity, 87.5%) for older children. AKIN stage 3 at admission predicted dialysis with a sensitivity of 92% and specificity of 84.2%. Urine output had the highest accuracy for dialysis prediction (sensitivity, 100%; specificity, 95.3%). Initial serum creatinine concentration was the best laboratory predictor of dialysis, but the first 24 h diuresis was even better for this purpose. But, given that serum creatinine is an immediate available parameter, the cut-offs identified may label D + HUS children who will probably need dialysis, prompting early referral to centers able to provide dialysis.

Investigation of an outbreak of bloody diarrhea complicated with hemolytic uremic syndrome

In July–August 2009, eight patients with bloody diarrhea complicated by hemolytic uremic syndrome (HUS) were admitted to hospitals in Tbilisi, Georgia. We started active surveillance in two regions for bloody diarrhea and post-diarrheal HUS. Of 25 case-patients who developed HUS, including the initial 8 cases, half were ⩾15years old, 67% were female and seven (28%) died. No common exposures were identified. Among 20 HUS case-patients tested, Shiga toxin was detected in the stools of 2 patients (one with elevated serum IgG titers to several Escherichia coli serogroups, including O111 and O104). Among 56 persons with only bloody diarrhea, we isolated Shiga toxin-producing E. coli (STEC) O104:H4 from 2 and Shigella from 10; 2 had serologic evidence of E. coli O26 infection. These cases may indicate a previously unrecognized burden of HUS in Georgia. We recommend national reporting of HUS and improving STEC detection capacity.

Increased Recognition of Non-O157 Shiga Toxin–ProducingEscherichia coliInfections in the United States During 2000–2010: Epidemiologic Features and Comparison withE. coliO157 Infections

Shiga toxin-producing Escherichia coli (STEC) are an important cause of diarrhea and the major cause of postdiarrheal hemolytic uremic syndrome. Non-O157 STEC infections are being recognized with greater frequency because of changing laboratory practices. Foodborne Diseases Active Surveillance Network (FoodNet) site staff conducted active, population-based surveillance for laboratory-confirmed STEC infections. We assessed frequency and incidence of STEC infections by serogroup and examined and compared demographic factors, clinical characteristics, and frequency of international travel among patients. During 2000-2010, FoodNet sites reported 2006 cases of non-O157 STEC infection and 5688 cases of O157 STEC infections. The number of reported non-O157 STEC infections increased from an incidence of 0.12 per 100,000 population in 2000 to 0.95 per 100,000 in 2010; while the rate of O157 STEC infections decreased from 2.17 to 0.95 per 100,000. Among non-O157 STEC, six serogroups were most commonly reported: O26 (26%), O103 (22%), O111 (19%), O121 (6%), O45 (5%), and O145 (4%). Non-O157 STEC infections were more common among Hispanics, and infections were less severe than those caused by O157 STEC, but this varied by serogroup. Fewer non-O157 STEC infections were associated with outbreaks (7% versus 20% for O157), while more were associated with international travel (14% versus 3% for O157). Improved understanding of the epidemiologic features of non-O157 STEC infections can inform food safety and other prevention efforts. To detect both O157 and non-O157 STEC infections, clinical laboratories should routinely and simultaneously test all stool specimens submitted for diagnosis of acute community-acquired diarrhea for O157 STEC and for Shiga toxin and ensure that isolates are sent to a public health laboratory for serotyping and subtyping.

Risk Factors for Development of Hemolytic Uremic Syndrome in a Cohort of Adult Patients with STEC 0104:H4 Infection

The outbreak of Shiga toxin producing E.coli O104:H4 in northern Germany in 2011 was one of the largest worldwide and involved mainly adults. Post-diarrheal hemolytic uremic syndrome (HUS) occurred in 22% of STEC positive patients. This study’s aim was to assess risk factors for HUS in STEC-infected patients and to develop a score from routine hospital parameters to estimate patient risks for developing HUS. In a cohort analysis, adult patients with STEC infection were included in five participating hospitals in northern Germany between May and July 2011. Clinical data were obtained from questionnaires and medical records, laboratory data were extracted from hospitals’ electronic data systems. HUS was defined as thrombocytopenia, hemolytic anemia and acute renal dysfunction. Random forests and multivariate logistic regression were used to identify risk factors for HUS and develop a score using the estimated coefficients as weights. Among 259 adults with STEC infection, vomiting (OR 3.48,95%CI 1.88–6.53), visible blood in stools (OR 3.91,95%CI1.20–16.01), age above 75 years (OR 3.27, 95%CI 1.12–9.70) and elevated leukocyte counts (OR 1.20, 95%CI 1.10–1.31, per 1000 cells/mm3) were identified as independent risk factors for HUS. A score using these variables has an area under the ROC curve of 0.74 (95%CI 0.68–0.80). Vomiting, visible blood in stools, higher leukocyte counts, and higher age indicate increased risk for developing HUS. A score using these variables might help to identify high risk patients who potentially benefit from aggressive pre-emptive treatment to prevent or mitigate the devastating consequences of HUS.