Editorial commentary: Escherichia coli O104:H4 and hemolytic uremic syndrome: the analysis begins

Clostridium septicum infection complicating Hemolytic-Uremic Syndrome: a case report and review of the literature

Clostridium septicum (C. septicum) is a zoonotic bacillus found in 2.8% of healthy human stools. In humans, it can cause serious infections such as bacteremia, myonecrosis, and encephalitis by spreading through the bloodstream. Reports of Shiga toxin-producing Escherichia Coli-related hemolytic-uremic syndrome complicated by C. septicum superinfection are rare, likely because colonic microangiopathic lesions by Shiga toxin-producing Escherichia Coli facilitate bacterial dissemination. Only 13 cases of Shiga toxin-producing Escherichia Coli-related hemolytic-uremic syndrome with C. septicum superinfection have been reported to date, according to our litterature review, with a 50% mortality rate. The lack of clinico-laboratory clues suggesting this condition makes the diagnosis challenging. For these reasons C. septicum superinfection usually goes undiagnosed in patients with Shiga toxin-producing Escherichia Coli-related hemolytic-uremic syndrome, and results in unfavorable outcomes. In this paper, we describe the case of a 5-year-old girl admitted for Shiga toxin-producing Escherichia Coli-related hemolytic-uremic syndrome who developed C. septicum coinfection leading to a fatal outcome. We carried out a review of the available literature on C. septicum infection complicating Shiga toxin-producing Escherichia Coli-related hemolytic-uremic syndrome and we compared the clinical features of the observed cases with those of an historical cohort of uncomplicated Shiga toxin-producing Escherichia Coli-related hemolytic-uremic syndrome. The mechanisms of superinfection are still unclear and clinical features are indistinguishable from those of uncomplicated Shiga toxin-producing Escherichia Coli-related hemolytic-uremic syndrome. However, rapid deterioration of clinical conditions and evidence of neurological involvement, associated with abnormal radiological findings, require immediate management. Although therapeutic approaches have not been directly compared, neurosurgical treatment of amenable lesions may improve the clinical outcome of patients with C. septicum-hemolytic-uremic syndrome.

Frequency of neurological involvement in patients with/without diarrhea hemolytic uremic syndrome: A Systematic review and meta-analysis

Background: Diarrhea-associated-hemolytic-uremic-syndrome (D+HUS) is a common from of HUS. Central-nervous-system (CNS) involvement is one of the most common extrarenal organ involvements in children with D+HUS. This systematic review and meta-analysis aim to recognize the frequency of neurological complications in pts with HUS. Methods: Databases of PubMed, Embase, and Web of Science were searched systematically to find the papers on neurological involvement in HUS pts. Two researchers independently assessed the papers' quality and extracted data. CMA v. 2.2.064. was used for data analysis. Heterogeneity was evaluated using the I-squared (I2) test, and a fixed/random-effects model was used when appropriate. Results: In this review, 21 studies including 2,189 participants with a median age between 1.3-40-year-old, entered the meta-analysis. The meta-analysis in D+HUS patients indicated 27.0% with neurological complications (95% CI, 22.0%-32.6%), 25.5% of symptoms weren't categorized (95% CI, 15.9%-38.3%), 20.8% of them developed the seizures (95% CI, 2.3%-74.4%). In D-HUS pts, 20.8% of them were presented neurological symptoms (95% CI, 17.9%-24.0%), of which 29.0% weren't categorized (95% CI, 19.2%-41.2%), 17.5% of pts got into coma (95% CI, 9.6%-29.7%), 5.6 % showed hemiparesis (95% CI, 2.8%-10.9%), 17.2% experienced lethargy (95% CI, 5.2%-44.1%), 30.5% developed the seizures (95% CI, 18.2%-46.2%), 7.4% manifested speech abnormalities (95% CI, 0.2%-7.22%), 6.4% of D-HUS pts presented visual-disturbances (95% CI, 3.4%-11.6%). Conclusion: This systematic review and meta-analysis indicated more than one-fourth of both D+HUS and D-HUS patients were presented with neurological symptoms, and the most prevalent symptoms were seizures, which can lead to an epilepsy sequel.

Case-management protocol for bloody diarrhea as a model to reduce the clinical impact of Shiga toxin-producing Escherichia coli infections. Experience from Southern Italy

To describe an operating protocol for bloody diarrhea (BD) in a pediatric population as a rapid response to a public health threat represented by an excess of pediatric HUS cases in the Apulia region (Southern Italy) starting from 2013. The protocol was set up with the goal of correct clinical management of Shiga toxin-producing Escherichia coli (STEC) infections, reductions in subsequent cases of hemolytic uremic syndrome (HUS), and improved short- and long-term disease outcomes. The protocol consisted of rapid hospitalization of children with bloody diarrhea (BD), hematochemical laboratory tests every 12–24 hours, and prompt laboratory diagnosis of STEC. No antibiotics were recommended until diagnosis. Children positive for STEC infections underwent early vigorous volume expansion. In June–December 2018, 438 children with BD were hospitalized, of which 53 (12.1%) had a STEC infection. The most common serogroups were O26 (36.1%), O111 (23.0%), and O157 (14.8%). Thirty-one samples carried the stx2 gene. Four cases evolved into HUS (7.5%), all with favorable outcome despite neurological involvement in two cases. Prompt and accurate laboratory diagnosis of STEC infections is of the utmost importance in patients with BD for correct clinical management. The strict adherence to the protocol could reduce the progression rate of STEC infections to HUS and prevents complications. Enhanced BD surveillance may help reduce cases of pediatric HUS in Southern Italy.

Haemolytic uraemic syndrome - a rare case report of bloody diarrhoea in adults

BACKGROUND

Haemolytic uraemic syndrome is a rarely seen in adults often leading to critical illness. This case highlights how difficult it can be to establish a diagnosis and treat when a patient presents with bloody diarrhoea.

CASE PRESENTATION

A 17-year-old Iraqi man presented to the emergency department with abdominal pain and bloody diarrhoea. He was initially treated as acute appendicitis, undergoing an appendectomy but following a recurrence in his symptoms a colonoscopy was performed. A diagnosis of shiga toxin-producing Escherichia coli leading to HUS was suspected following histology obtained at colonoscopy and this was confirmed on antibody testing. Despite intravenous fluids and supportive therapy the patient's symptoms and condition deteriorated. He developed seizures and acute renal failure requiring intubation and plasma exchange in the intensive care setting. He eventually required treatment with ecluzimab therapy; a monoclonal antibody and subsequently made a full recovery.

CONCLUSIONS

Haemolytic uraemic syndrome is a triad of progressive renal failure, thrombocytopenia and haemolytic anaemia which is a condition rarely seen in adults. It is usually associated with an E. coli infection and supportive therapy remains the mainstay of treatment.

A pediatric neurologic assessment score may drive the eculizumab-based treatment of Escherichia coli-related hemolytic uremic syndrome with neurological involvement

BACKGROUND

Thrombotic microangiopathy (TMA) is a clinical syndrome encompassing a large group of rare but severe disorders including thrombotic thrombocytopenic purpura (TTP) and both typical and atypical forms of hemolytic uremic syndrome (HUS). The key role of the complement system is well known in TTP and atypical HUS, but recent reports describe its involvement in the pathogenesis of HUS secondary to gastrointestinal infections due to Shiga toxin-producing Escherichia coli (STEC).

METHODS

TMA mainly affects the kidney, but extra-renal complications are frequently described. The involvement of the central nervous system (CNS) represents often a life-threatening condition and it can result in serious long-term disability in HUS patients who overcome the acute phase of illness. In the present study, we retrospectively analyzed a pediatric cohort of a single tertiary pediatric hospital in Southern Italy, in which this complication occurred in 12/54 children (22% of cases), of whom five with severe neurological involvement had been successfully treated with eculizumab.

RESULTS

The great clinical variability of brain injury in our cohort has led us to retrospectively build a "neurological score" useful to assess the clinical severity of neurologic involvement. Subjects with higher neurologic score due to the most severe CNS involvement resulted in the group of patients early treated with eculizumab, obtaining a good clinical response (four out five patients). In conclusion, the early treatment with eculizumab in children with severe neurological involvement during STEC-HUS was associated with complete regression of both acute kidney injury (AKI) and neurological lesions observed at magnetic resonance imaging (MRI).

CONCLUSIONS

A "neurological score" may be a useful tool to drive the early treatment of CNS complications in STEC-HUS with eculizumab, although future perspective controlled studies are urgently needed to validate this therapeutic approach.

Postinfectious Hemolytic Uremic Syndrome

Post-infectious hemolytic uremic syndrome (HUS) is caused by specific pathogens in patients with no identifiable HUS-associated genetic mutation or autoantibody. The majority of episodes is due to infections by Shiga toxin (Stx) producing Escherichia coli (STEC). This chapter reviews the epidemiology and pathogenesis of STEC-HUS, including bacterial-derived factors and host responses. STEC disease is characterized by hematological (microangiopathic hemolytic anemia), renal (acute kidney injury) and extrarenal organ involvement. Clinicians should always strive for an etiological diagnosis through the microbiological or molecular identification of Stx-producing bacteria and Stx or, if negative, serological assays. Treatment of STEC-HUS is supportive; more investigations are needed to evaluate the efficacy of putative preventive and therapeutic measures, such as non-phage-inducing antibiotics, volume expansion and anti-complement agents. The outcome of STEC-HUS is generally favorable, but chronic kidney disease, permanent extrarenal, mainly cerebral complication and death (in less than 5 %) occur and long-term follow-up is recommended. The remainder of this chapter highlights rarer forms of (post-infectious) HUS due to S. dysenteriae, S. pneumoniae, influenza A and HIV and discusses potential interactions between these pathogens and the complement system.

Outbreaks of non-O157 Shiga toxin-producing Escherichia coli infection: USA

Non-O157 Shiga toxin-producing Escherichia coli (STEC) infections are increasingly detected, but sources are not well established. We summarize outbreaks to 2010 in the USA. Single-aetiology outbreaks were defined as ⩾2 epidemiologically linked culture-confirmed non-O157 STEC infections; multiple-aetiology outbreaks also had laboratory evidence of ⩾2 infections caused by another enteric pathogen. Twenty-six states reported 46 outbreaks with 1727 illnesses and 144 hospitalizations. Of 38 single-aetiology outbreaks, 66% were caused by STEC O111 (n = 14) or O26 (n = 11), and 84% were transmitted through food (n = 17) or person-to-person spread (n = 15); food vehicles included dairy products, produce, and meats; childcare centres were the most common setting for person-to-person spread. Of single-aetiology outbreaks, a greater percentage of persons infected by Shiga toxin 2-positive strains had haemolytic uraemic syndrome compared with persons infected by Shiga toxin 1-only positive strains (7% vs. 0·8%). Compared with single-aetiology outbreaks, multiple-aetiology outbreaks were more frequently transmitted through water or animal contact.

HUS and TTP in Children

This review describes the epidemiology, pathophysiology, presentation, clinical causes, treatment, and long-term prognosis of pediatric patients who present with thrombotic microangiopathy. The focus is on hemolytic uremic syndrome and thrombotic thrombocytopenic purpura, the most common phenotypes of thrombotic microangiopathy.

New insights into Shiga toxin-mediated endothelial dysfunction in hemolytic uremic syndrome

Shiga toxin-producing E. coli represents a significant global health concern, especially as hypervirulent pathogens surface amidst outbreaks of hemolytic uremic syndrome (HUS). Shiga toxin (Stx) is key in the microangiopathic events underlying the disease and its central role is underscored by the unprecedented HUS outbreak in Germany in 2011. The mechanisms of Stx-mediated endothelial dysfunction have been a major focus of research that has contributed to the current understanding of the pathogenic changes in endothelial phenotype leading to HUS. Among the newer concepts are Stx-mediated gene regulation in the absence of protein synthesis inhibition, a potential role for complement activation, and accumulating evidence for detectable serum markers before the onset of the classic clinical features of HUS. Further investigation of newer therapeutic targets and potential prognostic markers is essential to assess their utility in mitigating disease and/or predicting outcomes and will provide an improved overall understanding of HUS pathogenesis.

Enterohemorrhagic Escherichia coli Infections and the Hemolytic-Uremic Syndrome

Enterohemorrhagic Escherichia coli (EHEC; Shiga toxin/verotoxin-producing E. coli) can cause bloody diarrhea and the hemolytic-uremic syndrome (HUS), typically following consumption of contaminated food (including ground beef, leafy greens, and sprouts) and water. Often associated with foodborne outbreaks, EHEC possess unique virulence factors that facilitate effective colonization of the human gastrointestinal tract and subsequent release of Shiga toxin. This article reviews the epidemiology, pathogenesis, clinical presentation, treatment, and prevention of EHEC infections, focusing on E. coli O157:H7, the serotype most common in North America, and E. coli O104:H4, the serotype responsible for the EHEC outbreak in Germany in 2011.

Renal and neurological involvement in typical Shiga toxin-associated HUS

Shiga toxin-producing Escherichia coli-associated haemolytic uraemic syndrome (STEC-HUS) is one of the most important causes of acute kidney injury in patients of all ages, especially in children. It can occur sporadically or in outbreaks. STEC-HUS is a systemic illness caused by toxin-mediated injury to the vascular endothelium and a generalized inflammatory response. The kidney and the brain are the two primary target organs. Nearly 40% of patients with STEC-HUS require at least temporary renal replacement therapy and up to 20% will have permanent residual kidney dysfunction. Neurological injury can be sudden and severe and is the most frequent cause of acute mortality in patients with STEC-HUS. Over the past 30 years, a wide range of inflammatory mediators have been linked to the pathogenesis of STEC-HUS and associated renal and neurological complications. Recently, evidence has accumulated that abnormal activation of the alternative pathway of complement occurs in patients with STEC-HUS. In the large outbreak of STEC-HUS caused by E. coli O104:H4 that occurred in Germany in May 2011, a large number of patients received eculizumab, a monoclonal antibody directed against C5, in an open-label manner. We describe the experience with eculizumab under these emergent circumstances at one large centre.