Update on hemolytic uremic syndrome: Diagnostic and therapeutic recommendations

[Clinical efficacy of eculizumab as treatment of gemcitabine-induced thrombotic microangiopathy: A case report]

INTRODUCTION

Gemcitabine-induced thrombotic microangiopathy is a rare event whose management is not yet consensual. The use of eculizumab could be of interest.

CASE REPORT

A 68-year-old woman was treated by gemcitabine as adjuvant chemotherapy of a pancreatic adenocarcinoma. Two months later, the patient presented with mechanical hemolytic anemia, thrombocytopenia and high blood pressure that led to the diagnosis of thrombotic microangiopathy. Gemcitabine was stopped. Plasma exchange therapy was introduced since hematological and renal parameters had worsened. As clinical efficacy was insufficient, eculizumab was introduced at a dose of 900 mg per week 4 times, then 1200 mg every 2 weeks. Symptoms along with hematological and nephrological analysis were back to physiological standards after 7 intravenous injections.

CONCLUSION

Eculizumab seems to be an effective treatment against gemcitabine-induced thrombotic microangiopathy in case of severe hematological and renal injuries associated with a lack of response to plasma exchange therapy.

Fecal diagnostics in combination with serology: best test to establish STEC-HUS

BACKGROUND

In the majority of pediatric patients, the hemolytic-uremic syndrome (HUS) is caused by an infection with Shiga toxin-producing Escherichia coli (STEC), mostly serotype O157. It is important to discriminate between HUS caused by STEC and complement-mediated HUS (atypical HUS) due to differences in treatment and outcome. As STEC and its toxins can only be detected in the patient's stool for a short period of time after disease onset, the infectious agent may go undetected using only fecal diagnostic tests. Serum antibodies to lipopolysaccharide (LPS) of STEC persist for several weeks and may therefore be of added value in the diagnosis of STEC.

METHODS

All patients with clinical STEC-HUS who were treated at Radboud University Medical Center between 1990 and 2014 were included in this retrospective single-center study. Clinical and diagnostic microbiological data were collected. Immunoglobulin M (IgM) antibodies against LPS of STEC serotype O157 were detected by a serological assay (ELISA).

RESULTS

Data from 65 patients weres available for analysis. Fecal diagnostic testing found evidence of an STEC infection in 34/63 patients (54 %). Serological evidence of STEC O157 was obtained in an additional 16 patients. This is an added value of 23 % (p < 0.0001) when the serological antibody assay is used in addition to standard fecal diagnostic tests to confirm the diagnosis STEC-HUS. This added value becomes especially apparent when the tests are performed more than 7 days after the initial manifestation of the gastrointestinal symptoms.

CONCLUSIONS

The serological anti-O157 LPS assay clearly makes a positive contribution when used in combination with standard fecal diagnostic tests to diagnose STEC-HUS and should be incorporated in clinical practice.

Neurological Manifestations of Renal Diseases in Children in Qazvin/ Iran

OBJECTIVE

Renal diseases are one of the most common causes of referrals and admissions of children, hence it is important to know their neurological presentations. This study aimed to determine neurological presentations of renal diseases in children.

MATERIAL & METHODS

A total of 634 children with renal diseases, admitted to Qazvin Pediatric Hospital, Qazvin, central Iran from 2011 to 2013 were studied. Neurological presentations of patients were established and the results were analyzed using statistical tests.

RESULTS

Neurological presentations were found in 18 (2.8%) out of 634 patients, of whom 15 had febrile seizures, two thromboembolism, and one encephalopathy. Among patients with urinary tract infection (UTI), 2.6% had febrile seizures, 11.1% of those with glomerulonephritis had encephalopathy, and 3.7% of those with nephrotic syndrome had cerebral thromboembolism.

CONCLUSION

Results showed neurological presentations in 2.8% of children with renal diseases, and febrile seizure as the most common presentation.

Escherichia coli O121:H19 infection identified on microagglutination assay and PCR

Non-O157 Shiga toxin-producing Escherichia coli (STEC) strains are increasingly recognized as foodborne pathogens that trigger hemolytic uremic syndrome (HUS). The detection and isolation of these strains is important, but distinguishing their bacteriological profiles is difficult. A 2-year-old girl developed HUS with mild renal involvement 22 days after consuming barbecued meat. Clinical and laboratory findings gradually improved without specific treatment. Because neither enterohemorrhagic E. coli (EHEC) nor Shiga toxins were detected in stool cultures in a clinical laboratory and the patient tested negative for circulating antibodies to O157 lipopolysaccharide, the case was initially diagnosed as probable atypical HUS. Subsequent serodiagnostic microagglutination assay and polymerase chain reaction-based molecular testing, however, indicated the presence of the EHEC O121:H19 strain with stx2. Thus, to correctly diagnose and treat HUS, a system for detecting non-O157 STEC in a clinical setting is urgently needed.

HUS and the case for complement

Hemolytic-uremic syndrome (HUS) is a thrombotic microangiopathy that is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and renal failure. Excess complement activation underlies atypical HUS and is evident in Shiga toxin-induced HUS (STEC-HUS). This Spotlight focuses on new knowledge of the role of Escherichia coli-derived toxins and polyphosphate in modulating complement and coagulation, and how they affect disease progression and response to treatment. Such new insights may impact on current and future choices of therapies for STEC-HUS.

Hemolytic uremic syndrome

Hemolytic uremic syndrome (HUS) is a clinical syndrome characterized by the triad of thrombotic microangiopathy, thrombocytopenia, and acute kidney injury. Hemolytic uremic syndrome represents a heterogeneous group of disorders with variable etiologies that result in differences in presentation, management and outcome. In recent years, better understanding of the HUS, especially those due to genetic mutations in the alternative complement pathway have provided an update on the terminology, classification, and treatment of the disease. This review will provide the updated classification of the disease and the current diagnostic and therapeutic approaches on the complement-mediated HUS in addition to STEC-HUS which is the most common cause of the HUS in childhood.

Hemolytic uremic syndrome

Hemolytic uremic syndrome (HUS) is a clinical syndrome characterized by the triad of thrombotic microangiopathy, thrombocytopenia, and acute kidney injury. Hemolytic uremic syndrome represents a heterogeneous group of disorders with variable etiologies that result in differences in presentation, management and outcome. In recent years, better understanding of the HUS, especially those due to genetic mutations in the alternative complement pathway have provided an update on the terminology, classification, and treatment of the disease. This review will provide the updated classification of the disease and the current diagnostic and therapeutic approaches on the complement-mediated HUS in addition to STEC-HUS which is the most common cause of the HUS in childhood.

Cutaneous and renal glomerular vasculopathy as a cause of acute kidney injury in dogs in the UK

To describe the signalment, clinicopathological findings and outcome in dogs presenting with acute kidney injury (AKI) and skin lesions between November 2012 and March 2014, in whom cutaneous and renal glomerular vasculopathy (CRGV) was suspected and renal thrombotic microangiopathy (TMA) was histopathologically confirmed. The medical records of dogs with skin lesions and AKI, with histopathologically confirmed renal TMA, were retrospectively reviewed. Thirty dogs from across the UK were identified with clinicopathological findings compatible with CRGV. These findings included the following: skin lesions, predominantly affecting the distal extremities; AKI; and variably, anaemia, thrombocytopaenia and hyperbilirubinaemia. Known causes of AKI were excluded. The major renal histopathological finding was TMA. All thirty dogs died or were euthanised. Shiga toxin was not identified in the kidneys of affected dogs. Escherichia coli genes encoding shiga toxin were not identified in faeces from affected dogs. CRGV has previously been reported in greyhounds in the USA, a greyhound in the UK, without renal involvement, and a Great Dane in Germany. This is the first report of a series of non-greyhound dogs with CRGV and AKI in the UK. CRGV is a disease of unknown aetiology carrying a poor prognosis when azotaemia develops.

Towards nano-diagnostics for bacterial infections

Sensitive, specific and rapid diagnosis of infectious diseases is essential for effective and economic medical care. Focused medical treatment of the patient enabled by pathogen-specific diagnosis may benefit the patient, may reduce cost, and may minimize the risk of drug resistance development. The rapid progress in micro and nanotechnologies contributes to the development of novel diagnostic methods. This critical review assesses emerging nanotechnologies for diagnosis of bacterial infection in developed and developing countries on the background of the current state of the art and includes particular challenges and pitfalls posed by a number of specific pathogens.

Atypical hemolytic uremic syndrome post-kidney transplantation: two case reports and review of the literature

Atypical hemolytic uremic syndrome (aHUS) is a rare disorder characterized by over-activation and dysregulation of the alternative complement pathway. Its estimated prevalence is 1–2 per million. The disease is characterized by thrombotic microangiopathy, which causes anemia, thrombocytopenia, and acute renal failure. aHUS has more severe course compared to typical (infection-induced) HUS and is frequently characterized by relapses that leads to end stage renal disease. For a long time, kidney transplantation for these patients was contraindicated because of high rate of recurrence and subsequent renal graft loss. The post-kidney transplantation recurrence rate largely depends on the pathogenetic mechanisms involved. However, over the past several years, advancements in the understanding and therapeutics of aHUS have allowed successful kidney transplantation in these patients. Eculizumab, which is a complement C5 antibody that inhibits complement factor 5a and subsequent formation of the membrane-attack complex, has been used in prevention and treatment of post-transplant aHUS recurrence. In this paper, we present two new cases of aHUS patients who underwent successful kidney transplantation in our center with the use of prophylactic and maintenance eculizumab therapy that have not been published before. The purpose of reporting these two cases is to emphasize the importance of using eculizumab as a prophylactic therapy to prevent aHUS recurrence post-transplant in high-risk patients. We will also review the current understanding of the genetics of aHUS, the pathogenesis of its recurrence after kidney transplantation, and strategies for prevention and treatment of post-transplant aHUS recurrence.

Consequences of hemolytic uremic syndrome among hemodialysis patients

Background

Hemolytic uremic syndrome (HUS) is characterized by hemolytic anemia, low platelets, and renal impairment and is mediated by thrombotic microangiopathy (TMA). A common perception is that HUS becomes dormant in dialysis patients with end-stage renal disease (ESRD). We analyzed patients in a large dialysis organization to understand the potential consequences and burden of HUS.

Methods

We identified patients with ESRD ascribed to HUS and those with ESRD ascribed to another cause (control patients) who received hemodialysis or peritoneal dialysis from 01 January 2007 to 31 December 2012. Outcomes were survival, hospitalization, and longitudinal laboratory values associated with TMA, including lactate dehydrogenase, red cell distribution width (RDW), platelets, and hemoglobin.

Results

HUS patients (n = 217) were propensity-score matched 1:5 to control patients (n = 1,085) for age, gender, race, dry weight, insurance, access, comorbidities, and Charlson comorbidity index. Compared to control patients, HUS patients had significantly greater risk for hospitalizations overall (RR = 2.3, p = 0.004) and hospitalization for hematologic (RR = 5.6, p = 0.001), cardiovascular (RR = 2.1, p = 0.02), and pancreatic (RR = 7.9, p = 0.04) causes. HUS patients also had evidence of ongoing TMA: higher lactate dehydrogenase and RDW, lower platelets and hemoglobin, and more frequent lactate dehydrogenase spikes.

Conclusions

Dialysis patients with HUS were at significantly higher risk than matched control patients for hospitalizations due to cardiovascular, hematologic, and pancreatic disease, which were associated with ongoing TMA. Additional studies are needed to determine whether targeted therapy for HUS reduces hospitalizations.

Serogroup-specific bacterial engineered glycoproteins as novel antigenic targets for diagnosis of shiga toxin-producing-escherichia coli-associated hemolytic-uremic syndrome

Human infection with Shiga toxin-producing Escherichia coli (STEC) is a major cause of postdiarrheal hemolytic-uremic syndrome (HUS), a life-threatening condition characterized by hemolytic anemia, thrombocytopenia, and acute renal failure. E. coli O157:H7 is the dominant STEC serotype associated with HUS worldwide, although non-O157 STEC serogroups can cause a similar disease. The detection of anti-O157 E. coli lipopolysaccharide (LPS) antibodies in combination with stool culture and detection of free fecal Shiga toxin considerably improves the diagnosis of STEC infections. In the present study, we exploited a bacterial glycoengineering technology to develop recombinant glycoproteins consisting of the O157, O145, or O121 polysaccharide attached to a carrier protein as serogroup-specific antigens for the serological diagnosis of STEC-associated HUS. Our results demonstrate that using these antigens in indirect ELISAs (glyco-iELISAs), it is possible to clearly discriminate between STEC O157-, O145-, and O121-infected patients and healthy children, as well as to confirm the diagnosis in HUS patients for whom the classical diagnostic procedures failed. Interestingly, a specific IgM response was detected in almost all the analyzed samples, indicating that it is possible to detect the infection in the early stages of the disease. Additionally, in all the culture-positive HUS patients, the serotype identified by glyco-iELISAs was in accordance with the serotype of the isolated strain, indicating that these antigens are valuable not only for diagnosing HUS caused by the O157, O145, and O121 serogroups but also for serotyping and guiding the subsequent steps to confirm diagnosis.

[Diagnostic and therapeutic guidelines of thrombotic microangiopathies of the Spanish Apheresis Group]

Thrombotic microangiopathies (TMA) are disorders defined by the presence of a microangiopathic hemolytic anemia (with the characteristic hallmark of schistocytes in the peripheral blood smear), thrombocytopenia and organ malfunction of variable intensity. Thrombotic thrombocytopenic purpura and hemolytic uremic syndrome are the most important forms of TMA and, without the adequate treatment, they are associated with high morbimortality. In recent years, significant advances in the knowledge of the pathophysiology of TMA have occurred. Those advances have allowed us to move from a syndromic diagnosis with a similar treatment to all entities to the search of etiologic diagnosis which would lead to a specific treatment, finally leading to a better outcome of the patient. This document pretends to summarize the current status of knowledge of the pathophysiology of TMA and the therapeutic options available, and to offer a diagnostic and therapeutic practical tool to the professionals caring for the patients.

New functional and structural insights from updated mutational databases for complement factor H, Factor I, membrane cofactor protein and C3

aHUS (atypical haemolytic uraemic syndrome), AMD (age-related macular degeneration) and other diseases are associated with defective AP (alternative pathway) regulation. CFH (complement factor H), CFI (complement factor I), MCP (membrane cofactor protein) and C3 exhibited the most disease-associated genetic alterations in the AP. Our interactive structural database for these was updated with a total of 324 genetic alterations. A consensus structure for the SCR (short complement regulator) domain showed that the majority (37%) of SCR mutations occurred at its hypervariable loop and its four conserved Cys residues. Mapping 113 missense mutations onto the CFH structure showed that over half occurred in the C-terminal domains SCR-15 to -20. In particular, SCR-20 with the highest total of affected residues is associated with binding to C3d and heparin-like oligosaccharides. No clustering of 49 missense mutations in CFI was seen. In MCP, SCR-3 was the most affected by 23 missense mutations. In C3, the neighbouring thioester and MG (macroglobulin) domains exhibited most of 47 missense mutations. The mutations in the regulators CFH, CFI and MCP involve loss-of-function, whereas those for C3 involve gain-of-function. This combined update emphasizes the importance of the complement AP in inflammatory disease, clarifies the functionally important regions in these proteins, and will facilitate diagnosis and therapy.

A new compilation of 324 mutations in four major proteins from the complement alternative pathway reveals mutational hotspots in factor H and complement C3, and less so in factor I and membrane cofactor protein. Their associations with function are discussed.

36-year-old female with catastrophic antiphospholipid syndrome treated with eculizumab: a case report and review of literature

Catastrophic antiphospholipid syndrome (CAPS) is a rare but potentially life-threatening condition characterized by diffuse vascular thrombosis, leading to multiple organ failure developing over a short period of time in the presence of positive antiphospholipid antibodies (aPL). CAPS is a severe form of antiphospholipid syndrome, developing in about 1% of cases of classic antiphospholipid syndrome, manifesting as microangiopathy, affecting small vessels of multiple organs. It is acute in onset, with majority of cases developing thrombocytopenia and less frequently hemolytic anemia and disseminated intravascular coagulation. Lupus anticoagulant and anticardiolipin antibodies have been reported as predominant antibodies associated with CAPS. Treatment options often utilized in CAPS include anticoagulation, steroids, plasma exchange, cyclophosphamide therapy, and intravenous immunoglobulin therapy. Even though the reported incidence of this condition is considered to be low, the mortality rate is approaching 50%. The high rate of mortality should warrant greater awareness among clinicians for timely diagnosis and treatment of this life-threatening condition. Studies have shown that complement activation plays a key role in the pathogenesis of aPL mediated thrombosis in CAPS. We report a case of a 36-year-old female admitted with clinical and laboratory findings consistent with CAPS successfully treated with eculizumab, a terminal complement inhibitor.

Molecular typing of Escherichia coli O157:H7 isolates from Swedish cattle and human cases: population dynamics and virulence

While all verotoxin-producing Escherichia coli O157:H7 bacteria are considered potential pathogens, their genetic subtypes appear to differ in their levels of virulence. The aim of this study was to compare the distribution of subtypes of E. coli O157:H7 in the cattle reservoir and in human cases with and without severe complications in order to gain clues about the relationship between subtype and relative virulence. A lineage-specific polymorphism assay (LSPA-6), multilocus variable-number tandem-repeat analysis (MLVA), and a novel real-time PCR assay to identify clade 8 were applied to a large and representative set of isolates from cattle from 1996 to 2009 (n = 381) and human cases from 2008 to 2011 (n = 197) in Sweden. Draft genome sequences were produced for four selected isolates. The E. coli O157:H7 isolates in Swedish cattle generally belonged to four groups with the LSPA-6 profiles 211111 (clade 8/non-clade 8), 213111, and 223323. The subtype composition of the cattle isolates changed dramatically during the study period with the introduction and rapid spread of the low-virulence 223323 subtype. The human cases presumed to have been infected within the country predominantly carried isolates with the profiles 211111 (clade 8) and 213111. Cases progressing to hemolytic-uremic syndrome (HUS) were mostly caused by clade 8, with MLVA profiles consistent with Swedish cattle as the source. In contrast, infections contracted abroad were caused by diverse subtypes, some of which were associated with a particular region. The work presented here confirms the high risk posed by the clade 8 variant of E. coli O157:H7. It also highlights the dynamic nature of the E. coli O157:H7 subtype composition in animal reservoirs and the importance of this composition for the human burden of disease.

Differing tales of two patients after receiving a kidney transplant from a donor with disseminated intravascular coagulation

In order to decrease the time on the deceased donor kidney wait list and to have more organs available, criteria for acceptable organs for transplant could be made less stringent. There are reports of successful recipient outcomes using kidney donors presenting with disseminated intravascular coagulation (DIC). We report a unique circumstance where two patients received kidneys from the same deceased donor who had DIC; one patient developed thrombotic microangiopathy (TMA) while the other did not. This difference in outcome may indicate that both donor and recipient factors contribute to the development of posttransplant TMA.

Management of hemolytic-uremic syndrome in children

Acute renal failure associated with a fulminant, life-threatening systemic disease is rare in previously healthy young children; however, when it occurs, the most common cause is hemolytic-uremic syndrome (HUS). In most cases (90%), this abrupt and devastating illness is a result of ingestion of food or drink contaminated with pathogens that produce very potent toxins. Currently, there are no proven treatment options that can directly inactivate the toxin or effectively interfere with the cascade of destructive events triggered by the toxin once it gains access to the bloodstream and binds its receptor. However, HUS is self-limited, and effective supportive management during the acute phase is proven to be a life saver for children affected by HUS. A minority of childhood HUS cases, approximately 5%, are caused by various genetic mutations causing uncontrolled activation of the complement system. These children, who used to have a poor prognosis leading to end-stage renal disease, now have access to exciting new treatment options that can preserve kidney function and avoid disease recurrences. This review provides a summary of the current knowledge on the epidemiology, pathophysiology, and clinical presentation of childhood HUS, focusing on a practical approach to best management measures.