Is Plasma Exchange Efficacious in Shiga Toxin‐Associated Hemolytic Uremic Syndrome? A Narrative Review of Current Evidence

Successful application of eculizumab in typical haemolytic uraemic syndrome

A woman in her 40s with no medical history presented on hospital day #0 with 3 days of epigastric pain, nausea, vomiting and bloody diarrhoea. Initial blood work demonstrated acute kidney injury with metabolic acidosis with an elevated anion gap, thrombocytopenia, an elevated lactate dehydrogenase, and an undetectable haptoglobin. She was quickly diagnosed with haemolytic uraemic syndrome from Shiga toxin-producing O157:H7 Escherichia coli Her microangiopathic haemolytic anaemia and renal failure progressively worsened and only improved after the initiation of eculizumab, a monoclonal antibody directed against complement component C5. We report a case of Shiga toxin-producing E. coli-haemolytic uraemia syndrome with a complement-mediated component.

Eculizumab for Shiga-toxin-induced hemolytic uremic syndrome in adults with neurological involvement

The role of eculizumab in treating Shiga-toxin-producing Escherichia coli (STEC) hemolytic uremic syndrome (HUS) patients with neurological involvement remains unclear. We describe two distinctly different STEC-HUS patients with neurologic involvement successfully managed with eculizumab, and perform a literature review of all published cases. Both patients had complete resolution of neurological symptoms after initiation of eculizumab. Eighty patients with STEC-HUS treated with eculizumab were identified in the literature, 68.7% had complete resolution of neurological symptoms. Based on our experience and literature review, three prevailing themes were noted: 1) Early eculizumab administration optimized neurological outcomes, 2) Symptom resolution may not be immediate, neurological symptoms may initially worsen before improvement, and 3) Plasma exchange yielded no benefit. Early administration of eculizumab may reverse neurotoxicity in patients with STEC-HUS.

Therapeutic plasma exchange in paediatric nephrology in Ireland

BACKGROUND

Therapeutic plasma exchange (TPE) is utilised in the management of a limited number of paediatric renal conditions. Despite its widespread acceptance and advancements in the practice of apheresis, there remains a paucity of data pertaining to paediatrics. We present a large retrospective review of our cohort of paediatric patients undergoing TPE for renal indications, outlining their outcomes and complications.

METHODS

A retrospective chart review was conducted for all patients (under 16 years) undergoing TPE for renal conditions between January 2002 and June 2019 in Ireland. Demographic and clinical data were extracted, with patients anonymised and stratified according to their pathology.

RESULTS

A total of 58 patients were identified. A total of 1137 exchanges were performed using heparin sodium anticoagulation. The median age was 35.5 months (IQR 18-110 months). The leading indication was neurological involvement in Shiga toxin-producing Escherichia coli haemolytic uraemic syndrome (STEC-HUS) (n = 29). Complications (minor or major) occurred in 65.5% (n = 38) of patients, with most experiencing minor complications 58.6% (n = 34). Asymptomatic hypocalcaemia was the most common complication in 43.1% (n = 25).

CONCLUSIONS

Our experience of TPE, spanning 1137 exchanges, proved a safe, well-tolerated therapy. Most complications were minor, and with therapy conducted in specialised centres, there are very low levels of adverse events.

Eculizumab in severe Shiga toxin-mediated haemolytic uraemic syndrome

Shiga toxin (Stx)-producing Escherichia coli-mediated haemolytic uraemic syndrome is a primary thrombotic microangiopathy, typified by the development of microangiopathic haemolytic anaemia, thrombocytopaenia and acute renal failure. It is a leading cause of acute renal failure in paediatrics, with a second peak in prevalence in adults over the age of 60. Presentations of Stx-producing E. coli-mediated haemolytic uraemic syndrome in young adults are rare. We present the case of a previously well female in her early 30s presenting with Stx-producing E. coli-mediated haemolytic uraemic syndrome with severe renal and neurological manifestations. Eculizumab was administered due to the severity of presentation and disease trajectory refractory to initial supportive therapy. A significant clinical and biochemical improvement was observed following eculizumab.

Hemolytic Uremic Syndrome-Induced Acute Kidney Injury Treated via Immunomodulation with the Selective Cytopheretic Device

INTRODUCTION

Shiga-toxin associated-hemolytic uremic syndrome (STEC-HUS) is a severe cause of acute kidney injury (AKI) in children. Although most children recover, about 5% die and 30% develop chronic renal morbidity. HUS pathophysiology includes activated neutrophils damaging vascular endothelial cells. Therapeutic immunomodulation of activated neutrophils may alter the progression of disease. We present 3 pediatric patients treated with the selective cytopheretic device (SCD).

METHODS

We describe a 12 y.o. (patient 1) and two 2 y.o. twins (patients 2 and 3) with STEC-HUS requiring continuous renal replacement therapy (CRRT) who were enrolled in two separate studies of the SCD.

RESULTS

Patient 1 presented with STEC-HUS causing AKI and multisystem organ failure and received 7 days of SCD and CRRT treatment. After SCD initiation, the patient had gradual recovery of multi-organ dysfunction, with normal kidney and hematologic parameters at 60-day follow-up. Patients 2 and 3 presented with STEC-HUS with AKI requiring dialysis. Each received 24 h of SCD therapy. Thereafter, both gradually improved, with normalization (patient 2) and near-normalization (patient 3) of kidney function at 60-day follow-up.

CONCLUSION

Immunomodulatory treatment with the SCD was associated with improvements in multisystem stigmata of STEC-HUS-induced AKI and was well-tolerated without any device-related adverse events.

HUS and TTP: traversing the disease and the age spectrum

Hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenia purpura (TTP) are rare diseases sharing a common pathological feature, thrombotic microangiopathy (TMA). TMA is characterized by microvascular thrombosis with consequent thrombocytopenia, microangiopathic hemolytic anemia and/or multiorgan dysfunction. In the past, the distinction between HUS and TTP was predominantly based on clinical grounds. However, clinical presentation of the two syndromes often overlaps and, the differential diagnosis is broad. Identification of underlying pathogenic mechanisms has enabled the classification of these syndromes on a molecular basis: typical HUS caused by Shiga toxin-producing Escherichia coli (STEC-HUS); atypical HUS or complement-mediated TMA (aHUS/CM-TMA) associated with genetic or acquired defects leading to dysregulation of the alternative pathway (AP) of complement; and TTP that results from a severe deficiency of the von Willebrand Factor (VWF)-cleaving protease, ADAMTS13. The etiology of TMA differs between pediatric and adult patients. Childhood TMA is chiefly caused by STEC-HUS, followed by CM-TMA and pneumococcal HUS (Sp-HUS). Rare conditions such as congenital TTP (cTTP), vitamin B12 metabolism defects, and coagulation disorders (diacylglycerol epsilon mutation) present as TMA chiefly in children under 2 years of age. In contrast secondary causes and acquired ADAMT13 deficiency are more common in adults. In adults, compared to children, diagnostic delays are more frequent due to the wide range of differential diagnoses. In this review we focus on the three major forms of TMA, STEC-HUS, aHUS and TTP, outlining the clinical presentation, diagnosis and management of the affected patients, to help highlight the salient features and the differences between adult and pediatric patients which are relevant for management.

Diagnosis and Treatment for Shiga Toxin-Producing Escherichia coli Associated Hemolytic Uremic Syndrome

Shiga toxin-producing Escherichia coli (STEC)-associated hemolytic uremic syndrome (STEC-HUS) is a clinical syndrome involving hemolytic anemia (with fragmented red blood cells), low levels of platelets in the blood (thrombocytopenia), and acute kidney injury (AKI). It is the major infectious cause of AKI in children. In severe cases, neurological complications and even death may occur. Treating STEC-HUS is challenging, as patients often already have organ injuries when they seek medical treatment. Early diagnosis is of great significance for improving prognosis and reducing mortality and sequelae. In this review, we first briefly summarize the diagnostics for STEC-HUS, including history taking, clinical manifestations, fecal and serological detection methods for STEC, and complement activation monitoring. We also summarize preventive and therapeutic strategies for STEC-HUS, such as vaccines, volume expansion, renal replacement therapy (RRT), antibiotics, plasma exchange, antibodies and inhibitors that interfere with receptor binding, and the intracellular trafficking of the Shiga toxin.

Thrombotic microangiopathy in children

The syndrome of thrombotic microangiopathy (TMA) is a clinical-pathological entity characterized by microangiopathic hemolytic anemia, thrombocytopenia, and end organ involvement. It comprises a spectrum of underlying etiologies that may differ in children and adults. In children, apart from ruling out shigatoxin-associated hemolytic uremic syndrome (HUS) and other infection-associated TMA like Streptococcus pneumoniae-HUS, rare inherited causes including complement-associated HUS, cobalamin defects, and mutations in diacylglycerol kinase epsilon gene must be investigated. TMA should also be considered in the setting of solid organ or hematopoietic stem cell transplantation. In this review, acquired and inherited causes of TMA are described with a focus on particularities of the main causes of TMA in children. A pragmatic approach that may help the clinician tailor evaluation and management is provided. The described approach will allow for early initiation of treatment while waiting for the definitive diagnosis of the underlying TMA.

Neurological involvement in children with hemolytic uremic syndrome

Our objective was to establish the rate of neurological involvement in Shiga toxin-producing Escherichia coli-hemolytic uremic syndrome (STEC-HUS) and describe the clinical presentation, management and outcome. A retrospective chart review of children aged ≤ 16 years with STEC-HUS in Children's Health Ireland from 2005 to 2018 was conducted. Laboratory confirmation of STEC infection was required for inclusion. Neurological involvement was defined as encephalopathy, focal neurological deficit, and/or seizure activity. Data on clinical presentation, management, and outcome were collected. We identified 240 children with HUS; 202 had confirmed STEC infection. Neurological involvement occurred in 22 (11%). The most common presentation was seizures (73%). In the neurological group, 19 (86%) were treated with plasma exchange and/or eculizumab. Of the 21 surviving children with neurological involvement, 19 (91%) achieved a complete neurological recovery. A higher proportion of children in the neurological group had renal sequelae (27% vs. 12%, P = .031). One patient died from multi-organ failure.Conclusion: We have identified the rate of neurological involvement in a large cohort of children with STEC-HUS as 11%. Neurological involvement in STEC-HUS is associated with good long-term outcome (complete neurological recovery in 91%) and a low case-fatality rate (4.5%) in our cohort. What is Known: • HUS is associated with neurological involvement in up to 30% of cases. • Neurological involvement has been reported as predictor of poor outcome, with associated increased morbidity and mortality. What is New: • The incidence of neurological involvement in STEC-HUS is 11%. • Neurological involvement is associated with predominantly good long-term outcome (90%) and a reduced case-fatality rate (4.5%) compared to older reports.

Shiga Toxin-Associated Hemolytic Uremic Syndrome in Adults, France, 2009-2017

We conducted a retrospective study on hemolytic uremic syndrome caused by Shiga toxin–producing Escherichia coli (STEC) in 96 adults enrolled in the cohort of the National Reference Center for Thrombotic Microangiopathies network in France during 2009–2017. Most infections were caused by STEC strains not belonging to the O157 or O104 serogroups. Thirty (31.3%) patients had multiple risk factors for thrombotic microangiopathy. In total, 61 (63.5%) patients required dialysis, 50 (52.1%) had a serious neurologic complication, 34 (35.4%) required mechanical ventilation, and 19 (19.8%) died during hospitalization. We used multivariate analysis to determine that the greatest risk factors for death were underlying immunodeficiency (hazard ratio 3.54) and severe neurologic events (hazard ratio 3.40). According to multivariate analysis and propensity score-matching, eculizumab treatment was not associated with survival. We found that underlying conditions, especially immunodeficiency, are strongly associated with decreased survival in adults who have hemolytic uremic syndrome caused by STEC.

Therapeutic plasma exchange in critically ill children: experience of the pediatric intensive care unit of two centers in Chile

INTRODUCTION

Therapeutic plasma exchange (TPE) is an extracorporeal blood purification technique used in a wide spectrum of diseases. We aim to review the indications, complications, and outcomes of critically ill children who received TPE and to compare a membrane versus centrifugal method in this cohort.

METHODS

A retrospective observational study in two pediatric intensive care units in Chile during eight years (2011-2019) Results: A total of 36 patients underwent 167 TPE sessions (20 centrifugation and 16 membrane-based). The more frequent indications for TPE were autoimmune neurological diseases in 14 cases, renal diseases (9), and rheumatological disorders (5). 58 % of children received other immunomodulatory therapy. According to ASFA, 45 % of cases were I-II category, 50 % to III, and 5% not classified. Response to treatment was complete in 64 % (23/36) and partial in 33 % (12/36). Complications occurred in 17.4 % of sessions, and the most frequent was transient hypotension during the procedure. Overall survival at discharge from the PICU was 92 %. Patients who received TPE as a single therapy (n = 26) survived 96 %. The clinical outcomes between the two apheresis methods were similar. Survivors had a significantly lower PELOD score on admission (14.5 vs. 6.5, p = 0.004).

CONCLUSIONS

TPE is mainly indicated as a rescue treatment in neurological autoimmune diseases refractory to conventional immunomodulatory treatment. Complications in critically ill children are mild and low. The outcome in children requiring TPE as a single therapy is good, and no differences were observed with centrifugation or membrane method.

Severely ill pediatric patients with Shiga toxin-associated hemolytic uremic syndrome (STEC-HUS) who suffered from multiple organ involvement in the early stage

BACKGROUND

Shiga toxin-producing Escherichia coli-associated hemolytic uremic syndrome (STEC-HUS) is the main cause of pediatric acute kidney injury (AKI) in Argentina. Endothelial injury is the trigger event in the microangiopathic process. The host inflammatory response to toxin and E. coli lipopolysaccharide (LPS) is involved in disease pathophysiology.

METHODS

This retrospective study describes pediatric STEC-HUS patients with multiorgan involvement at the initial phase of disease. A retrospective study of critically ill HUS patients with evidence of E. coli infection was conducted through a period of 15 years.

RESULTS

Forty-four patients 35.4 ± 4.1 months were admitted to the intensive care unit for 21 ± 2 days. Mechanical ventilation was required in 41 patients, early inotropic support in 37, and 28 developed septic shock. Forty-one patients required kidney replacement therapy for 12 ± 1 days. Forty-one patients showed neurological dysfunction. Dilated cardiomyopathy was demonstrated in 3 patients, left ventricular systolic dysfunction in 4, and hypertension in 17. Four patients had pulmonary hemorrhage, and acute respiratory distress syndrome in 2. Colectomy for transmural colonic necrosis was performed in 3 patients. Thirty-seven patients were treated with therapeutic plasma exchange, and 28 patients received methylprednisolone (10 mg/kg for 3 days). Of the surviving 32 patients, neurological sequelae were seen in 11 and chronic kidney failure in 5.

CONCLUSIONS

Severe clinical outcome at onset suggests an amplified inflammatory response after exposure to Shiga toxin and/or E. coli LPS. STEC-HUS associated with severe neurological involvement, hemodynamic instability, and AKI requires intensive care and focused therapy.

Plasma exchange and thrombotic microangiopathies: From pathophysiology to clinical practice

Thrombotic microangiopathy (TMA) brings together many diseases that have a commonality in the apparition of mechanical hemolysis with consuming thrombopenia. In all cases, these diseases can be life threatening, thereby justifying the implementation of treatment as an emergency. First-line treatment represents plasma exchange. This treatment has proven efficiency in improving the vital patient's and functional prognosis. However, the administration methods of plasma exchange can be redefined in light of the understanding of the pathophysiology of TMA. The aim of this review is to try to define, from pathophysiology, the place of plasma exchanges in the modern therapeutic arsenal of TMA.

Typical and Atypical Hemolytic Uremic Syndrome in the Critically Ill

Hemolytic uremic syndrome is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Disseminated intravascular coagulation, thrombotic thrombocytopenic purpura, and hemolytic uremic syndrome have a similar clinical presentation. Diagnostic needs to be prompt to decrease mortality, because identifying the different disorders can help to tailor specific, effective therapies. However, diagnosis is challenging and morbidity and mortality remain high, especially in the critically ill population. Development of clinical prediction scores and rapid diagnostic tests for hemolytic uremic syndrome based on mechanistic knowledge are needed to facilitate early diagnosis and assign timely specific treatments to patients with hemolytic uremic syndrome variants.

Hemolytic uremic syndrome in a developing country: Consensus guidelines

BACKGROUND

Hemolytic uremic syndrome (HUS) is a leading cause of acute kidney injury in children. Although international guidelines emphasize comprehensive evaluation and treatment with eculizumab, access to diagnostic and therapeutic facilities is limited in most developing countries. The burden of Shiga toxin-associated HUS in India is unclear; school-going children show high prevalence of anti-factor H (FH) antibodies. The aim of the consensus meeting was to formulate guidelines for the diagnosis and management of HUS in children, specific to the needs of the country.

METHODS

Four workgroups performed literature review and graded research studies addressing (i) investigations, biopsy, genetics, and differential diagnosis; (ii) Shiga toxin, pneumococcal, and infection-associated HUS; (iii) atypical HUS; and (iv) complement blockade. Consensus statements developed by the workgroups were discussed during a consensus meeting in March 2017.

RESULTS

An algorithm for classification and evaluation was developed. The management of Shiga toxin-associated HUS is supportive; prompt plasma exchanges (PEX) is the chief therapy in patients with atypical HUS. Experts recommend that patients with anti-FH-associated HUS be managed with a combination of PEX and immunosuppressive medications. Indications for eculizumab include incomplete remission with plasma therapy, life-threatening features, complications of PEX or vascular access, inherited defects in complement regulation, and recurrence of HUS in allografts. Priorities for capacity building in regional and national laboratories are highlighted.

CONCLUSIONS

Limited diagnostic capabilities and lack of access to eculizumab prevent the implementation of international guidelines for HUS in most developing countries. We propose practice guidelines for India, which will perhaps be applicable to other developing countries.