Escherichia coli encoding Shiga toxin subtype Stx2f causing human infections in England, 2015-2022

Introduction. Shiga toxin-producing Escherichia coli (STEC) belong to a diverse group of gastrointestinal pathogens defined by the presence of Shiga toxin genes (stx) of which there are at least ten subtypes (Stx1a-Stx1d and Stx2a-Stx2g).Gap Statement. Initially thought to be associated with mild symptoms, more recently STEC encoding stx2f have been isolated from cases of haemolytic uraemic syndrome (HUS) and the clinical significance and public health burden require further investigation.Aim. We analysed clinical outcomes and genome-sequencing data linked to patients infected with STEC encoding-stx2f in England to assess the risk to public health.Methodology. One hundred and twelve E. coli (n=58 isolates encoded stx2f; n=54 isolates E. coli belonging to CC122 or CC722 that had eae but were negative for stx) isolated from patients' faecal specimens between 2015 and 2022 were genome sequenced and linked to epidemiological and clinical outcome data. All isolates were investigated for the presence of virulence genes and a maximum-likelihood phylogeny of isolates belonging to CC122 and CC722 was constructed.Results. There were 52 cases infected with STEC harbouring stx2f between 2015 and 2022, with the majority identified in 2022. Most cases resided in the North of England (n=39/52, 75 %), were female (n=31, 59.6 %) and/or aged five and under (n=29, 55.8 %). Clinical outcome data were available for 40/52 cases (76.9 %) and 7/40(17.5 %) were diagnosed with STEC-HUS. In the two most common clonal complexes, CC122 and CC722, the presence of the stx2f-encoding prophage correlated with the presence of additional virulence genes, astA, bfpA and cdt, located on an 85kbp IncFIB plasmid.Conclusions. Certain serotypes of E. coli harbouring stx2f cause severe clinical outcomes, including STEC-HUS. Public health advice and possible interventions are limited, as little is known about the animal and environmental reservoirs and transmission routes. We recommend more comprehensive and standardized collection of microbiological and epidemiological data, and routine sharing of sequencing data between public health agencies worldwide.

Molecular epidemiology, clinical features and significance of Shiga toxin detection from routine testing of gastroenteritis specimens

After introduction of faecal multiplex PCR that includes targets for stx1 and stx2 genes, we found stx genes were detected in 120 specimens from 111 patients over a 31-month period from 2018-2020 from a total of 14,179 separate tests performed. The proportion of stx1 only vs stx2 only vs stx1 and stx2 was 35%, 22% and 42%, respectively. There were 54 specimens which were culture positive, with 33 different serotypes identified, the predominant serotype being O157:H7 (19%). Eighty-two patients had clinical data available; we found a high rate of fever (35%), bloody diarrhoea (34%), acute kidney injury (27%), hospital admission (80%) and detection of faecal co-pathogens (23%). Only one patient developed haemolytic uraemic syndrome. We found no significant association with stx genotype and any particular symptom or complication. We found a significant association of serotypes O157:H7 and O26:H11 with bloody stool, but no significant association with any other symptom or complication.

The epidemiology of Shiga toxin-producing Escherichia coli O26:H11 (clonal complex 29) in England, 2014-2021

OBJECTIVES

We aimed to describe the genomic epidemiology of the foodborne gastrointestinal pathogen, Shiga toxin-producing Escherichia coli (STEC) serotype O26:H11 belonging to clonal complex 29 (CC29) in England.

METHODS

Between 01 January 2014 and 31 December 2021, 834 human isolates belonging to CC29 were sequenced at the UK Health Security Agency, and the genomic data was integrated with epidemiological data.

RESULTS

Diagnoses of STEC O26:H11 in England have increased each year from 19 in 2014 to 144 in 2021. Most isolates had the Shiga toxin subtype profiles stx1a (47%), stx1a,stx2a (n=24%) or stx2a (n=28%). Most cases were female (57%), and the highest proportion of cases belonged to the 0-5 age group (38%). Clinical symptoms included diarrhoea (93%), blood-stained stool (48%), and abdominal pain (74%). Haemolytic Uraemic Syndrome (HUS) was diagnosed in 40/459 (9%) cases and three children died. All isolates causing STEC-HUS had stx2a either alone (n=33) or in combination with stx1a (n=7).

CONCLUSIONS

STEC O26:H11 are a clinically significant, emerging threat to public health in England. Determining the true incidence and prevalence is challenging due to inconsistent national surveillance strategies. Improved diagnostics and surveillance algorithms are required to monitor the true burden, detect outbreaks and to implement effective interventions.

Diarrhoea-associated haemolytic uraemic syndrome and Shiga toxin-producing Escherichia coli infections in New Zealand children: Clinical features and short-term complications from a 23-year cohort study

BACKGROUND

Diarrhoea-associated haemolytic uraemic syndrome (D+HUS) is an important cause of acute kidney injury (AKI) in young children and it is most commonly associated with Shiga toxin-producing Escherichia coli (STEC). Gastrointestinal infections caused by STEC have been increasing in New Zealand over the past two decades, but little is known regarding the acute and short-term outcomes of New Zealand children who develop D+HUS.

AIM

To describe the clinical characteristics, complications and short-term outcomes of New Zealand children with D+HUS identified between 1 January 1998 and 31 December 2020.

METHODS

The New Zealand Paediatric Surveillance Unit sends out a monthly survey to all practising paediatricians regarding conditions under active surveillance. Paediatricians caring for a child aged 0-15 years of age with D+HUS over the prior month were requested to report their patient. Reporting clinicians were then contacted by the principal investigator and sent a questionnaire requesting patient clinical and laboratory information.

RESULTS

Two hundred and twenty-six children had D+HUS; median age 2.8 years (interquartile range 1.7-4.9). Acute dialysis was required in 128/226 (56.2%) of children for a median of 9 days (range 1-38). Children with shorter diarrhoeal prodrome, higher neutrophil count and haemoglobin had a longer duration of dialysis. Seizures occurred in 31/226 (13.7%) and were not associated with a greater HUS severity score. Acute mortality was 1.3%, all resulting from thrombotic microangiopathic cerebral injury.

CONCLUSION

D+HUS is a major cause of AKI in previously healthy young children. Earlier recognition of STEC infections in young children may reduce the need for dialysis and other extra-renal complications. The New Zealand incidence of acute dialysis, other major complications and mortality are consistent with other reported studies.

Diagnosis and treatment of thrombotic microangiopathy

Thrombotic microangiopathy (TMA) is characterized by thrombocytopenia, microangiopathic haemolytic anaemia and end organ damage. TMAs have varying underlying pathophysiology and can therefore present with an array of clinical presentations. Renal involvement is common as the kidney is particularly susceptible to the endothelial damage and microvascular occlusion. TMAs require rapid assessment, diagnosis, and commencement of appropriate treatment due to the high morbidity and mortality associated with them. Ground-breaking research into the pathogenesis of TMAs over the past 20 years has driven the successful development of targeted therapeutics revolutionizing patient outcomes. This review outlines the clinical presentations, pathogenesis, diagnostic tests and treatments for TMAs.

Epidemiology and genomic analysis of Shiga toxin-producing Escherichia coli clonal complex 165 in the UK

Introduction. Shiga toxin-producing Escherichia coli (STEC) is a zoonotic, foodborne gastrointestinal pathogen that has the potential to cause severe clinical outcomes, including haemolytic uraemic syndrome (HUS). STEC-HUS is the leading cause of renal failure in children and can be fatal. Over the last decade, STEC clonal complex 165 (CC165) has emerged as a cause of STEC-HUS.Gap Statement. There is a need to understand the pathogenicity and prevalence of this emerging STEC clonal complex in the UK, to facilitate early diagnosis, improve clinical management, and prevent and control outbreaks.Aim. The aim of this study was to characterize CC165 through identification of virulence factors (VFs) and antimicrobial resistance (AMR) determinants in the genome and to integrate the genome data with the available epidemiological data to better understand the incidence and pathogenicity of this clonal complex in the UK.Methodology. All isolates belonging to CC165 in the archives at the UK public health agencies were sequenced and serotyped, and the virulence gene and AMR profiles were derived from the genome using PHE bioinformatics pipelines and the Centre for Genomic Epidemiology virulence database.Results. There were 48 CC165 isolates, of which 43 were STEC, four were enteropathogenic E. coli (EPEC) and one E. coli. STEC serotypes were predominately O80:H2 (n=28), and other serotypes included O45:H2 (n=9), O55:H9 (n=4), O132:H2 (n=1) and O180:H2 (n=1). All but one STEC isolate had Shiga toxin (stx) subtype stx2a or stx2d and 47/48 isolates had the eae gene encoding intimin involved in the intimate attachment of the bacteria to the human gut mucosa. We detected extra-intestinal virulence genes including those associated with iron acquisition (iro) and serum resistance (iss), indicating that this pathogen has the potential to translocate to extra-intestinal sites. Unlike other STEC clonal complexes, a high proportion of isolates (93%, 40/43) were multidrug-resistant, including resistance to aminoglycosides, beta-lactams, chloramphenicol, sulphonamides, tetracyclines and trimethoprim.Conclusion. The clinical significance of this clonal complex should not be underestimated. Exhibiting high levels of AMR and a combination of STEC and extra-intestinal pathogenic E. coli (ExPEC) virulence profiles, this clonal complex is an emerging threat to public health.

Haemolytic uraemic syndrome associated with pancreatitis: report of four cases and review of the literature

Background

The incidence of acute kidney injury (AKI) in patients with acute pancreatitis ranges from 15% to 40% and is associated with poor prognosis. Haemolytic uraemic syndrome (HUS) in the setting of acute pancreatitis is an uncommon association with fewer than 30 cases reported in the literature.

Methods

A retrospective review of the clinical records at our institution between January 1981 and December 2019 was carried out to identify patients with acute pancreatitis and HUS. Additionally, a literature review was conducted on this topic. The aims of the study were to describe the clinical course and outcomes of patients affected by this condition.

Results

Four cases of HUS following an acute pancreatitis were identified. The mean (±SD) age of the study group was 30 ± 6 years, all of which were males. Excessive alcohol consumption was the main cause of acute pancreatitis in all four patients. HUS with progressive AKI developed in a median interval of 2 days from the onset of pancreatitis (range 1-3 days). All patients required kidney replacement therapy during the course of follow-up. A kidney biopsy was performed in two patients, showing typical thrombotic microangiopathic features. One case was treated with eculizumab, whereas the rest were treated with supportive care and/or plasma exchange. A normalization of haematological parameters and complete recovery of kidney function were observed in all patients at last follow-up, although this improvement was significantly faster in the patient treated with eculizumab.

Conclusions

HUS may infrequently develop in patients with acute pancreatitis. An early identification of this complication is mandatory, and complement blockade with eculizumab may be associated with a faster kidney function recovery.

The emerging importance of Shiga toxin-producing Escherichia coli other than serogroup O157 in England

Introduction

Shiga toxin-producing Escherichia coli (STEC) can cause severe disease and large outbreaks. In England, the incidence and clinical significance of STEC serogroups other than O157 (non-O157) is unknown due to a testing bias for detection of STEC O157. Since 2013, the implementation of PCR to detect all STEC serogroups by an increasing number of diagnostic laboratories has led to an increase in the detection of non-O157 STEC.

Hypothesis/Gap statement

Due to a bias in testing methodologies to select for STEC serogroup O157 in frontline diagnostic laboratories in most countries, very little surveillance data have been previously generated on non-O157 STEC.

Aim

Five years (2014–2018) of STEC national surveillance data were extracted and descriptive analysis undertaken to assess disease severity of non-O157 STEC strains.

Methods

Data from 1 January 2014 to 31 December 2018 were extracted from the National Enhanced Surveillance System for STEC and analysed.

Results

The implementation of Gastrointestinal Polymerase Chain Reaction (GI-PCR) has resulted in a four-fold increase in the detection of non-O157 STEC cases between 2014 and 2018. There were 2579 cases infected with 97 different non-O157 serogroups. The gender distribution was similar amongst STEC O157 and non-O157 STEC cases with 57 and 56 % of cases being female respectively, but a significantly higher proportion of cases (P <0.001) under 5 years of age was observed among STEC O157 (22 %) cases compared to non-O157 STEC (14 %). The most common non-O157 serogroups were O26 (16 %), O146 (11 %), O91 (10 %), O128 (7 %), O103 (5 %) and O117 (3 %). Overall, rates of bloody diarrhoea were highest in O26 (44 %) and O103 (48 %) cases and lowest in STEC O117 cases (17 %). Strains harbouring Shiga toxin stx1a caused the highest proportion of diarrhoea (93 %) and caused the same level of bloody diarrhoea as stx2a (39 %). However, stx2a caused the highest proportion of vomiting (46 %), hospitalisation (49 %) and considerably more HUS (29 %) than other stx profiles.

Conclusion

The implementation of PCR targeting stx at diagnostic laboratories has shown that non-O157 STEC, most notably STEC O26, are an emerging risk to public health.

Thrombotic microangiopathy with renal injury: an approach for the general physician

Thrombotic microangiopathy with renal dysfunction is a haematological and renal emergency warranting urgent diagnosis and intervention. As the potential underlying causes may be complex, assessment and management can be challenging for treating clinicians, and a timely and collaborative approach between general physicians, haematologists and nephrologists may be extremely helpful in order to optimise clinical outcomes. This paper will aim to build an understanding of different potential presentations of thrombotic microangiopathies and provide a practical framework for diagnosis and management, using a case-based discussion format, for acute and general physicians. Some aspects of subsequent specialist management are also discussed.

Outcome of children with Shiga toxin-associated haemolytic uraemic syndrome treated with eculizumab: a matched cohort study

BACKGROUND

Treatment with eculizumab in Shiga toxin-associated haemolytic and uraemic syndrome (STEC-HUS) remains controversial despite its increasing utilization. The aim of our study was to evaluate the outcomes of children treated with eculizumab for STEC-HUS in a single-centre matched cohort study.

METHODS

Data were retrospectively collected from medical records of children diagnosed with STEC-HUS. The outcomes of patients treated with eculizumab for STEC-HUS were compared with those of a control group of untreated patients matched for age, sex and severity of acute kidney injury with a 1:2 matching scheme.

RESULTS

Eighteen children (median age 40.6 months) with STEC-HUS treated with eculizumab were compared with 36 matched control patients (median age 36.4 months) who did not receive eculizumab. All patients survived in the two groups. Within 1 month of HUS onset, the evolution of haematological and renal parameters did not differ between the two groups. At 12 months of follow-up, renal outcome was not significantly different between the two groups. At the last follow-up, the prevalence of decreased glomerular filtration rate in the eculizumab group (27%) was not statistically different from that in controls (38%), as was the prevalence of proteinuria and high blood pressure. Children who received eculizumab more often had extrarenal sequelae during follow-up. Eculizumab treatment appeared to be safe in children with STEC-HUS.

CONCLUSION

The benefit of eculizumab on renal and extrarenal outcomes in STEC-HUS could not be established based on our findings. However, efficacy and safety are not best assessed by the observational design and small sample size of our study. Randomized controlled trials are thus required to determine the efficacy of eculizumab in this indication.

Usefulness of automated fragmented red blood cell percentage in the diagnosis of paediatric haemolytic uraemic syndrome

INTRODUCTION

Presence of schistocytes in peripheral blood smear supporting haemolysis is important for diagnosis and decision-making in paediatric haemolytic uraemic syndrome (HUS). High observer dependency and requirement of expertise for peripheral smear evaluation propels us to think of other modalities to overcome these issues. We envisage that newer techniques like automated fragmented red blood cell percentage (FRC %), whose role has been described in transplant associated HUS and thrombotic thrombocytopenic purpura, can serve the purpose.

METHODS

Twenty-eight children with HUS after excluding secondary causes were enrolled in this study. Blood samples were analysed for FRC% at admission, using SYSMEX XN-1000 (Japan) haematology analyser, and simultaneously, schistocytes in peripheral smear were reported by a single expert haematopathologist.

RESULTS

Median age was 56 months ranging from 2 to 140 months. FRC% was elevated in 85.8% (n-24/28) with a mean of 4.56 ± 3.1%. FRC% had a sensitivity of 95.4% (C.I: 77.16% to 99.88%) in children who had FRC% >1.49% with an accuracy of 85.71% (C.I: 67.33% to 95.97%). However, specificity was only 50% (C.I: 11.81% to 88.19%) with a positive likelihood ratio of 1.91. Receiver-operator curve showed an AUC value of 0.841.

CONCLUSION

We suggest automated FRC% as a rapid and highly sensitive index for screening of paediatric HUS; however, a peripheral blood film examination is a must in cases with count >2% to avoid false positives as the index has low specificity.

Aliskiren and the dual complement inhibition concept

In this issue of Clinical Kidney Journal, Plasse et al. report on the use of high-dose aliskiren as an adjunct therapy in a patient treated with eculizumab for haemolytic uraemic syndrome (HUS). This follows the recent description of the complement factor 3 (C3) activating activity of the enzyme renin and the successful therapeutic use of the direct renin inhibitor aliskiren in three cases of C3 glomerulopathy/dense deposit disease. We discuss the potential clinical and pathophysiological implications of these reports on nephropathies linked to complement, from HUS to C3 glomerulopathy to immunoglobulin A nephropathy as well as the concept of dual complement inhibition for kidney disease.

Shiga toxin-producing Escherichia coli O26:H11 associated with a cluster of haemolytic uraemic syndrome cases in South Africa, 2017

INTRODUCTION

Shiga toxin-producing Escherichia coli (STEC) are foodborne pathogens that may cause diarrhoeal outbreaks and occasionally are associated with haemolytic-uraemic syndrome (HUS). We report on STEC O26:H11 associated with a cluster of four HUS cases in South Africa in 2017.

METHODOLOGY

All case-patients were female and aged 5 years and under. Standard microbiological tests were performed for culture and identification of STEC from specimens (human stool and food samples). Further analysis of genomic DNA extracted from bacterial cultures and specimens included PCR for specific virulence genes, whole-genome sequencing and shotgun metagenomic sequencing.

RESULTS

For 2/4 cases, stool specimens revealed STEC O26:H11 containing eae, stx2a and stx2b virulence genes. All food samples were found to be negative for STEC. No epidemiological links could be established between the HUS cases. Dried meat products were the leading food item suspected to be the vehicle of transmission for these cases, as 3/4 case-patients reported they had eaten this. However, testing of dried meat products could not confirm this.

CONCLUSION

Since STEC infection does not always lead to severe symptoms, it is possible that many more cases were associated with this cluster and largely went unrecognized.

Relative incidence of thrombotic thrombocytopenic purpura and haemolytic uraemic syndrome in clinically suspected cases of thrombotic microangiopathy

Background

Data are lacking on the relative incidence of thrombotic thrombocytopenic purpura (TTP), haemolytic uraemic syndrome (HUS) caused by Shiga toxin–producing Escherichia coli (STEC) and atypical HUS (aHUS) in patients presenting with thrombotic microangiopathies (TMAs).

Methods

This was a prospective, cross-sectional, multicentre and non-interventional epidemiological study. Patients fulfilling criteria for TMAs (platelet consumption, microangiopathic haemolytic anaemia and organ dysfunction) were included in the study. The primary objective was to assess the relative incidence of TTP, STEC-HUS, aHUS and ‘other’ physician-defined diagnoses. The secondary objective was to develop an algorithm to predict a severe deficiency in ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) activity (≤10%) using routine laboratory parameters. A post hoc classification using the recent Kidney Disease: Improving Global Outcomes diagnostic criteria was then undertaken to further classify patient groups.

Results

aHUS was diagnosed with a relative incidence of 61%, whereas TTP, STEC-HUS and ‘other’ were diagnosed in 13, 6 and 20% of patients, respectively. In the post hoc analysis, 27% of patients with a TMA were classified as ‘primary aHUS’ and 53% as ‘secondary aHUS’. Multivariate analysis revealed that severe deficiency in ADAMTS13 activity (≤10%) was unlikely to underlie TMA if platelet and serum creatinine were above threshold values of 30 × 10⁹/L and 1.8 mg/dL, respectively (negative predictive value of 92.3 and 98.1, respectively, if one or both values were above the threshold).

Conclusions

In this study, aHUS was the most common single diagnosis among patients presenting with a TMA. In the absence of an ADAMTS13 activity result, platelet count and serum creatinine may aid in the differential diagnosis.

Gemcitabine-induced haemolytic uraemic syndrome in pancreatic adenocarcinoma

A woman in her mid-70s with metastatic pancreatic adenocarcinoma presented with fatigue, nausea and bilateral leg swelling, 4 days after an intravenous gemcitabine infusion. Additional examination and laboratory tests showed mild hypertension, low haemoglobin, high lactate dehydrogenase, low platelet count and high serum creatinine. The patient was subsequently diagnosed with haemolytic uraemic syndrome (HUS), and gemcitabine administration was immediately ceased. The patient received a 5-day course of methylprednisolone, with a full recovery being made 10 days after diagnosis. Clinicians should be aware of the rare but serious complication of gemcitabine-induced HUS (GiHUS), as early diagnosis and management, which includes prompt discontinuation of gemcitabine, are crucial in promptly resolving this condition. This case report describes one treatment that can be used for the treatment of GiHUS, while briefly covering some other novel treatments that have been described in other studies.

Paediatric haemolytic uraemic syndrome related to Shiga toxin-producing Escherichia coli, an overview of 10 years of surveillance in France, 2007 to 2016

IntroductionHaemolytic uraemic syndrome (HUS) related to Shiga toxin-producing Escherichia coli (STEC) is the leading cause of acute renal failure in young children. In France, HUS surveillance in children aged < 15 years was implemented starting from 1996.AimWe present the results of this surveillance between 2007 and 2016.MethodsA voluntary nationwide network of 32 paediatric departments notifies cases. Two national reference centres perform microbiological STEC confirmation.ResultsOver the study period, the paediatric HUS incidence rate (IR) was 1.0 per 100,000 children-years, with a median of 116 cases/year. In 2011, IR peaked at 1.3 per 100,000 children-years, and decreased to 1.0 per 100,000 children-years in 2016. STEC O157 associated HUS peaked at 37 cases in 2011 and decreased to seven cases in 2016. Cases of STEC O26-associated HUS have increased since 2010 and STEC O80 associated HUS has emerged since 2012, with 28 and 18 cases respectively reported in 2016. Four STEC-HUS food-borne outbreaks were detected (three STEC O157 linked to ground beef and raw-milk cheese and one STEC O104 linked to fenugreek sprouts). In addition, two outbreaks related to person-to-person transmission occurred in distinct kindergartens (STEC O111 and O26).ConclusionsNo major changes in HUS IRs were observed over the study period of 10 years. However, changes in the STEC serogroups over time and the outbreaks detected argue for continuing epidemiological and microbiological surveillance.

Successful treatment of a Streptococcus pneumoniae-associated haemolytic uraemic syndrome by eculizumab

Haemolytic uraemic syndrome (HUS) is a rare complication of invasive infection by Streptococcus pneumoniae (SP-HUS), especially in adults. Here we report an unusual case of a 53-year-old man presenting SP-HUS with severe multivisceral involvement. After failure of supportive care and plasma exchanges, eculizumab (anti-C5 antibody) resulted in a favourable outcome.

Ongoing haemolytic uraemic syndrome (HUS) outbreak caused by sorbitol-fermenting (SF) Shiga toxin-producing Escherichia coli (STEC) O157, Germany, December 2016 to May 2017

We report an ongoing, protracted and geographically dispersed outbreak of haemolytic uraemic syndrome (HUS) and gastroenteritis in Germany, involving 30 cases since December 2016. The outbreak was caused by the sorbitol-fermenting immotile variant of Shiga toxin-producing (STEC) Escherichia coli O157. Molecular typing revealed close relatedness between isolates from 14 cases. One HUS patient died. Results of a case–control study suggest packaged minced meat as the most likely food vehicle. Food safety investigations are ongoing.

Haemolytic uraemic syndrome

Haemolytic uraemic syndrome (HUS) is defined by the simultaneous occurrence of nonimmune haemolytic anaemia, thrombocytopenia and acute renal failure. This leads to the pathological lesion termed thrombotic microangiopathy, which mainly affects the kidney, as well as other organs. HUS is associated with endothelial cell injury and platelet activation, although the underlying cause may differ. Most cases of HUS are associated with gastrointestinal infection with Shiga toxin-producing enterohaemorrhagic Escherichia coli (EHEC) strains. Atypical HUS (aHUS) is associated with complement dysregulation due to mutations or autoantibodies. In this review, we will describe the causes of HUS. In addition, we will review the clinical, pathological, haematological and biochemical features, epidemiology and pathogenetic mechanisms as well as the biochemical, microbiological, immunological and genetic investigations leading to diagnosis. Understanding the underlying mechanisms of the different subtypes of HUS enables tailoring of appropriate treatment and management. To date, there is no specific treatment for EHEC-associated HUS but patients benefit from supportive care, whereas patients with aHUS are effectively treated with anti-C5 antibody to prevent recurrences, both before and after renal transplantation.

Early findings in outbreak of haemolytic uraemic syndrome among young children caused by Shiga toxin-producing Escherichia coli, Romania, January to February 2016

As at 29 February 2016, 15 cases of haemolytic uraemic syndrome with onset between 25 January and 22 February were reported among children between five and 38 months in Romania, and three of them died. Cases were mostly from southern Romania. Six cases tested positive for Escherichia coli O26 by serology. Fruits, vegetables, meat and dairy products were among the possible common food exposures. Investigations are ongoing in Romania to control the outbreak.

Cancer-associated thrombotic microangiopathy

Cancer-associated thrombotic microangiopathy refers to a group of disorders characterised by microvascular thrombosis, thrombocytopenia, and ischaemic end-organ damage. Haemolytic uraemic syndrome and thrombotic thrombocytopenic purpura are the two major subtypes. It can be a manifestation of the malignancy itself or a complication of its therapy. The addition of several new drugs to the therapeutic armamentarium of cancer has brought to light several novel causative factors of this hitherto uncommon complication. This review covers the aetiology, pathogenesis, clinical manifestations, complications, and the management of cancer-associated thrombotic microangiopathy. Careful review of the patient’s medical records coupled with the correlation of clinical findings and laboratory reports can help clinch the diagnosis and institute appropriate treatment on time.

Risk of haemolytic uraemic syndrome caused by shiga-toxin-producing Escherichia coli infection in adult women in Japan

Shiga-toxin-producing Escherichia coli (STEC) infections usually cause haemolytic uraemic syndrome (HUS) equally in male and female children. This study investigated the localization of globotriaosylceramide (Gb3) in human brain and kidney tissues removed from forensic autopsy cases in Japan. A fatal case was used as a positive control in an outbreak of diarrhoeal disease caused by STEC O157:H7 in a kindergarten in Urawa in 1990. Positive immunodetection of Gb3 was significantly more frequent in female than in male distal and collecting renal tubules. To correlate this finding with a clinical outcome, a retrospective analysis of the predictors of renal failure in the 162 patients of two outbreaks in Japan was performed: one in Tochigi in 2002 and the other in Kagawa Prefecture in 2005. This study concludes renal failure, including HUS, was significantly associated with female sex, and the odds ratio was 4·06 compared to male patients in the two outbreaks. From 2006 to 2009 in Japan, the risk factor of HUS associated with STEC infection was analysed. The number of males and females and the proportion of females who developed HUS were calculated by age and year from 2006 to 2009. In 2006, 2007 and 2009 in adults aged >20 years, adult women were significantly more at risk of developing HUS in Japan.

Complement activation patterns in atypical haemolytic uraemic syndrome during acute phase and in remission

Atypical haemolytic uraemic syndrome (aHUS) is associated with (genetic) alterations in alternative complement pathway. Nevertheless, comprehensive evidence that the complement system in aHUS patients is more prone to activation is still lacking. Therefore, we performed a thorough analysis of complement activation in acute phase and in remission of this disease. Complement activation patterns of the aHUS patients in acute phase and in remission were compared to those of healthy controls. Background levels of complement activation products C3b/c, C3bBbP and terminal complement complex (TCC) were measured using enzyme-linked immunosorbent assay (ELISA) in ethylenediamine tetraacetic acid (EDTA) plasma. In vitro-triggered complement activation in serum samples was studied using zymosan-coating and pathway-specific assay. Furthermore, efficiencies of the C3b/c, C3bBbP and TCC generation in fluid phase during spontaneous activation were analysed. Patients with acute aHUS showed elevated levels of C3b/c (P < 0·01), C3bBbP (P < 0·0001) and TCC (P < 0·0001) in EDTA plasma, while values of patients in remission were normal, compared to those of healthy controls. Using data from a single aHUS patient with complement factor B mutation we illustrated normalization of complement activation during aHUS recovery. Serum samples from patients in remission showed normal in vitro patterns of complement activation and demonstrated normal kinetics of complement activation in the fluid phase. Our data indicate that while aHUS patients have clearly activated complement in acute phase of the disease, this is not the case in remission of aHUS. This knowledge provides important insight into complement regulation in aHUS and may have an impact on monitoring of these patients, particularly when using complement inhibition therapy.

Timing of eculizumab therapy for C3 glomerulonephritis

Eculizumab is an anti-C5 antibody that inhibits C5 cleavage and prevents the generation of the terminal complement complex C5b-9. Eculizumab is licensed to treat paroxysmal nocturnal haemoglobinuria or atypical haemolytic uraemic syndrome (aHUS). Clinical trials are ongoing for C3 glomerulopathy. Given the unfamiliarity of physicians with these rare diseases and the variability of clinical presentation, a delayed initiation of eculizumab therapy is common. Thus, the question arises as to what extent improvement of kidney function may be expected when patients have been dialysis dependent for weeks or months already when eculizumab is initiated. Furthermore, given the high cost and potential adverse effects of eculizumab, the question arises of when to stop therapy because of futility when patients with kidney-only manifestations remain dialysis dependent. In literature reports, eculizumab was stopped as early as after 3 weeks because the patient remained dialysis dependent. In this issue of CKJ, Inman et al. report on eculizumab-induced reversal of dialysis-dependent kidney failure from C3 glomerulonephritis, illustrating both the potential benefit of eculizumab for this complement-mediated disease and the need for lengthy therapy—dialysis independency was reached after 5 months of eculizumab. Indeed, there are reports of renal function recovery when eculizumab was initiated after 4 months on dialysis and of recovery of renal function 2.0–3.5 months after initiation of eculizumab in dialysis-dependent patients with C3 glomerulopathy or aHUS.

Cyclic-di-GMP signalling and biofilm-related properties of the Shiga toxin-producing 2011 German outbreak Escherichia coli O104:H4

In 2011, nearly 4,000 people in Germany were infected by Shiga toxin (Stx)-producing Escherichia coli O104:H4 with > 22% of patients developing haemolytic uraemic syndrome (HUS). Genome sequencing showed the outbreak strain to be related to enteroaggregative E. coli (EAEC), suggesting its high virulence results from EAEC-typical strong adherence and biofilm formation combined to Stx production. Here, we report that the outbreak strain contains a novel diguanylate cyclase (DgcX)--producing the biofilm-promoting second messenger c-di-GMP--that shows higher expression than any other known E. coli diguanylate cyclase. Unlike closely related E. coli, the outbreak strain expresses the c-di-GMP-controlled biofilm regulator CsgD and amyloid curli fibres at 37°C, but is cellulose-negative. Moreover, it constantly generates derivatives with further increased and deregulated production of CsgD and curli. Since curli fibres are strongly proinflammatory, with cellulose counteracting this effect, high c-di-GMP and curli production by the outbreak O104:H4 strain may enhance not only adherence but may also contribute to inflammation, thereby facilitating entry of Stx into the bloodstream and to the kidneys where Stx causes HUS.

Systematic review and meta-analysis of the proportion of Campylobacter cases that develop chronic sequelae

BACKGROUND

Understanding of chronic sequelae development after Campylobacter infection is limited. The objective of the study was to determine via systematic review and meta-analysis the proportion of Campylobacter cases that develop chronic sequelae.

METHODS

A systematic review of English language articles published prior to July 2011 located using Pubmed, Agricola, CabDirect, and Food Safety and Technology Abstracts. Observational studies reporting the number of Campylobacter cases that developed reactive arthritis (ReA), Reiter's syndrome (RS), haemolytic uraemic syndrome (HUS), irritable bowel syndrome (IBS), inflammatory bowel disease (IBD) ,Guillain Barré syndrome (GBS) or Miller Fisher syndrome (MFS) were included. Data extraction through independent extraction of articles by four reviewers (two per article). Random effects meta-analysis was performed and heterogeneity was assessed using the I(2) value. Meta-regression was used to explore the influence of study level variables on heterogeneity.

RESULTS

A total of 31 studies were identified; 20 reported on ReA, 2 reported on RS, 9 reported on IBS, 3 studies reported on IBD, 8 reported on GBS, 1 reported on MFS and 3 reported on HUS. The proportion of Campylobacter cases that developed ReA was 2.86% (95% CI 1.40% - 5.61%, I(2) = 97.7%), irritable bowel syndrome was 4.01% (95% CI 1.41% - 10.88%, I(2) = 99.2%). Guillain Barré syndrome was 0.07% (95% CI 0.03% - 0.15%, I(2) = 72.7%).

CONCLUSIONS

A significant number of Campylobacter cases develop a chronic sequela. However, results should be interpreted with caution due to the high heterogeneity.

Enteroaggregative Shiga toxin-producing Escherichia coli of serotype O104:H4 in Belgium and Luxembourg

In 2011, a large outbreak of infections caused by Shiga toxin-producing Escherichia coli (STEC) O104:H4 occurred in Germany. This exceptionally virulent strain combined virulence factors of enteroaggregative E. coli (EAggEC) and STEC. After the outbreak only a few sporadic cases of infection with this rare serotype were reported, most of which were related to travel to the Middle East or North Africa. Here we describe two cases of enteroaggregative STEC (Agg-STEC) O104:H4 infection that occurred in Belgium in 2012 and 2013 respectively. In both cases travel in a Mediterranean country preceded the infection. The first strain was isolated from the stool of a 42-year-old woman presenting bloody diarrhoea, who had travelled to Tunisia the week before. The second case involves a 14-year-old girl who, upon her return from Turkey to Belgium, suffered from an episode of bloody diarrhoea and haemolytic uraemic syndrome. Extended typing of the isolates with pulsed field gel electrophoresis revealed that the strains were closely related, though not exactly the same as the 2011 outbreak strain. This report supports the previously made hypothesis that Agg-STEC has a human reservoir and might be imported by travellers coming from an area where the pathogen is endemic. Furthermore, it emphasizes the concern that these bacteria may cause future outbreaks as evenly virulent O104:H4 isolates seem to be widespread.

Atypical haemolytic uraemic syndrome associated with a CD46 mutation triggered by Shigella flexneri

We present a case of haemolytic uraemic syndrome (HUS) triggered by Shigella flexneri. Of the Shigella species, only S. dysenteriae type 1 is said to produce Shiga toxin and consequently cause HUS. Investigation of the complement system in this patient revealed a CD46 mutation. In individuals with mutations in complement genes incomplete penetrance of atypical HUS (aHUS) is seen, suggesting that a trigger, such as infection, is required for disease to manifest. In an era of complement modulatory therapy for aHUS it is important to be alert to unusual presentations of diarrhoeal-associated disease.

Outbreak of Escherichia coli O104:H4 haemolytic uraemic syndrome in France: outcome with eculizumab

Background

An outbreak of haemolytic uraemic syndrome (HUS) due to Shiga toxin-secreting Escherichia coli (STEC) O104:H4 from contaminated fenugreek sprouts occurred in June 2011 near Bordeaux, France. In the context of this outbreak, all patients were treated with the monoclonal anti-C5 antibody, eculizumab.

Methods

The diagnosis of HUS was made based on haemolytic anaemia, low platelet count and acute kidney injury. Data were obtained from initial gastrointestinal symptoms to the end of follow-up 10 weeks after the start of eculizumab.

Results

Among 24 cases of STEC gastroenteritis, HUS developed in nine patients (eight adults and one child), 6 (median; range 3–12) days after digestive symptoms begun. The median (range) highest or lowest biological values were platelet count 26 (range 14–93) G/L; haemoglobin 6.6 (range 5–10.7) g/dL; LDH 1520 (range 510–2568) IU/L; creatinine 152 (range 48–797) µmol/L. All patients had extra-renal complications (liver 9, pancreas 5, brain 3 and heart 3). Two patients were dialysed, and one was ventilated. After failure of plasma exchange to increase platelets in the first three patients, eculizumab was administered in all nine patients, 0–4 days after HUS diagnosis (median 1 day). One patient with very severe neurological HUS received immunoadsorption. Outcome was favourable in all patients, with rapid normalization of haemoglobin, platelets, LDH levels, renal function and neurological improvement. There were no deaths and no serious adverse events related to eculizumab.

Conclusions

Early treatment of O104:H4 STEC-HUS by eculizumab was associated with a rapid and efficient recovery. Controlled prospective evaluation of eculizumab in STEC-HUS is warranted.

The oxidative stress induced in vivo by Shiga toxin-2 contributes to the pathogenicity of haemolytic uraemic syndrome

Typical haemolytic uraemic syndrome (HUS) is caused by Shiga toxin (Stx)-producing Escherichia coli infections and is characterized by thrombotic microangiopathy that leads to haemolytic anaemia, thrombocytopenia and acute renal failure. Renal or neurological sequelae are consequences of irreversible tissue damage during the acute phase. Stx toxicity and the acute inflammatory response raised by the host determine the development of HUS. At present there is no specific therapy to control Stx damage. The pathogenic role of reactive oxygen species (ROS) on endothelial injury has been largely documented. In this study, we investigated the in-vivo effects of Stx on the oxidative balance and its contribution to the development of HUS in mice. In addition, we analysed the effect of anti-oxidant agents as therapeutic tools to counteract Stx toxicity. We demonstrated that Stx induced an oxidative imbalance, evidenced by renal glutathione depletion and increased lipid membrane peroxidation. The increased ROS production by neutrophils may be one of the major sources of oxidative stress during Stx intoxication. All these parameters were ameliorated by anti-oxidants reducing platelet activation, renal damage and increasing survival. To conclude, Stx generates a pro-oxidative state that contributes to kidney failure, and exogenous anti-oxidants could be beneficial to counteract this pathogenic pathway.

[Thrombotic microangiopathy mimicking a heparin-induced thrombocytopenia]

We report a case of a 47 years old woman. In her case of medical history, there were vein thrombosis and an allergic to tinzaparin. The patient entered in critical care unit under medical supervision for a multivisceral infarction due to an arterial mesenteric, renal and splenic thrombosis. An heparinotherapy was introduced. A laparotomy was realized because of an occlusion. Small intestine necrozed was removed. 8 days after the introduction of the heparin, there was a thrombocytopenia. Considering the background and the initiale situation, an heparin-induced thrombocytopenia of type II (HTI) was suspected. Whereas the heparinotherapy was stopped, the thrombocytopenia maked worse. Biological tests infirmed HIT's diagnosis. A recurrent anemia in spite transfusions associated to a renal failure suggest a thrombotic microangiopathy which was secondary confirmed. The intensivist is sensibilized to evoke an heparin induced thrombocytopenia when there is a thrombocytopenia under heparin. However, he must not forget diagnosis of thrombocytopenia which required specific investigations and emergency treatment such as thrombotic microangiopathy.

Cisplatin-induced haemolytic uraemic syndrome associated with a novel intronic mutation of CD46 treated with eculizumab

A 2-year-old patient with a neuroblastoma developed haemolytic uraemic syndrome (HUS) following treatment with cisplatin and carboplatin. Following treatment with eculizumab, there was a substantial improvement in renal function with the recovery of the platelet count and the cessation of haemolysis. Subsequent investigations showed a novel, heterozygous CD46 splice site mutation with reduced peripheral blood neutrophil CD46 expression. Withdrawal of eculizumab was followed by the recurrence of disease activity, which resolved with re-introduction of therapy. Abnormal regulation of complement may be associated with other cases of cisplatin-induced HUS and treatment with eculizumab may be appropriate for other affected individuals.

The role of complement in Streptococcus pneumoniae-associated haemolytic uraemic syndrome

BACKGROUND

Atypical forms of haemolytic uraemic syndrome (aHUS) include HUS caused by defects in the regulation of alternative complement pathway and HUS linked to neuraminidase-producing pathogens, such as Streptococcus pneumoniae. Increasing data support a pathogenic role of neuraminidase in the development of S. pneumoniae-associated haemolytic uraemic syndrome (SP-HUS), but the role of complement has never been clarified in detail. Therefore, we aimed to investigate whether the pathologic complement profile and genetic risk factors of aHUS are present in patients with SP-HUS.

METHODS

Enrolling five patients with SP-HUS classical and alternative pathway activity, besides C3, C4, factors H, B, I and anti-factor H autoantibody levels were determined. The coding regions of CFH, CFI, CD46 (MCP), THBD, C3 and CFB genes were sequenced and the copy number of CFI, CD46, CFH and related genes were also analyzed.

RESULTS

We found that in the acute phase samples of SP-HUS patients, complement components C4, C3 and activity of the classical and alternative pathways were decreased, indicating severe activation and complement consumption, but most of these alterations normalized later in remission. Three of the patients carried mutations and risk haplotypes in complement-mediated aHUS associated genes. The identified mutations include a previously published CFI variant (P50A) and two novel ones in CFH (R1149X) and THBD (T44I) genes.

CONCLUSIONS

Our results suggest that severe complement dysregulation and consumption accompany the progress of invasive pneumococcal disease (IPD)-associated SP-HUS and genetic variations of complement genes may contribute to the development of this complication in a proportion of the affected patients.

Advances in our understanding of the pathogenesis of glomerular thrombotic microangiopathy

Glomerular thrombotic microangiopathy is a hallmark feature of haemolytic uraemic syndrome, the leading cause of acute renal failure in childhood. This paper is a review of the different mechanistic pathways that lead to this histological picture in the kidney. It will focus on atypical HUS and complement dysregulation, but will also highlight some other recent advances in our understanding of this condition, including the potential role of the molecule vascular endothelial growth factor-A (VEGF-A).

Haemolytic uraemic syndrome associated with H1N1 influenza

Haemolytic uraemic syndrome (HUS) is one of the two forms of thrombotic microangiopathies and is characterized by the triad of microangiopathic haemolytic anaemia, thrombocytopaenia, and acute renal failure. It has been associated with bacterial and viral infections as well as non-infective causes. We report a subject who presented with HUS associated with an influenza-like syndrome which was confirmed as an influenza A (H1N1) infection. There are reports of HUS associated with seasonal influenza, but there have been no reported cases of HUS after novel influenza A (H1N1) in the literature so far.

Disease recurrence in paediatric renal transplantation

Renal transplantation (Tx) is the treatment of choice for end-stage renal disease. The incidence of acute rejection after renal Tx has decreased because of improving early immunosuppression, but the risk of disease recurrence (DR) is becoming relatively high, with a greater prevalence in children than in adults, thereby increasing patient morbidity, graft loss (GL) and, sometimes, mortality rate. The current overall graft loss to DR is 7-8%, mainly due to primary glomerulonephritis (70-80%) and inherited metabolic diseases. The more typical presentation is a recurrence of the full disease, either with a high risk of GL (focal and segmental glomerulosclerosis 14-50% DR, 40-60% GL; atypical haemolytic uraemic syndrome 20-80% DR, 10-83% GL; membranoproliferative glomerulonephritis 30-100% DR, 17-61% GL; membranous nephropathy approximately 30% DR, approximately 50% GL; lipoprotein glomerulopathy approximately 100% DR and GL; primary hyperoxaluria type 1 80-100% DR and GL) or with a low risk of GL [immunoglobulin (Ig)A nephropathy 36-60% DR, 7-10% GL; systemic lupus erythematosus 0-30% DR, 0-5% GL; anti-neutrophilic cytoplasmic antibody (ANCA)-associated glomerulonephritis]. Recurrence may also occur with a delayed risk of GL, such as insulin-dependent diabetes mellitus, sickle cell disease, endemic nephropathy, and sarcoidosis. In other primary diseases, the post-Tx course may be complicated by specific events that are different from overt recurrence: proteinuria or cancer in some genetic forms of nephrotic syndrome, anti-glomerular basement membrane antibodies-associated glomerulonephritis (Alport syndrome, Goodpasture syndrome), and graft involvement as a consequence of lower urinary tract abnormality or human immunodeficiency virus (HIV) nephropathy. Some other post-Tx conditions may mimic recurrence, such as de novo membranous glomerulonephritis, IgA nephropathy, microangiopathy, or isolated specific deposits (cystinosis, Fabry disease). Adequate strategies should therefore be added to kidney Tx, such as donor selection, associated liver Tx, plasmatherapy, specific immunosuppression protocols. In such conditions, very few patients may be excluded from kidney Tx only because of a major risk of DR and repeated GL. In the near future the issue of DR after kidney Tx may benefit from alternatives to organ Tx, such as recombinant proteins, specific monoclonal antibodies, cell/gene therapy, and chaperone molecules.

Enterohaemorrhagic Escherichia coli and Shigella dysenteriae type 1-induced haemolytic uraemic syndrome

Haemolytic uraemic syndrome (HUS) can be classified according to the aetiology of the different disorders from which it is composed. The most prevalent form is that induced by shigatoxin producing Escherichia coli (STEC) and, in some tropical regions, by Shigella dysenteriae type 1. STEC cause a zoonosis, are widely distributed in nature, enter the food chain in different ways, and show regional differences. Not all STEC are human pathogens. Enterohaemorrhagic E. coli usually cause attachment and effacing lesions in the intestine. This is not essential, but production of a shigatoxin (Stx) is. Because Stx are encoded by a bacteriophage, this property is transferable to naïve strains. Laboratory methods have improved by identifying STEC either via the toxin or its bacteriophage. Shigella dysenteriae type 1 produces shigatoxin, identical to Stx-1, but also has entero-invasive properties that enterohaemorrhagic Escherichia coli (EHEC) do not. Shigella patients risk bacteremia and benefit from early antibiotic treatment, unlike those with EHEC.

Thrombotic thrombocytopenic purpura/haemolytic uraemic syndrome associated with clopidogrel: report of two new cases

Clopidogrel has been reported to be safe and effective in reducing vascular events. Nevertheless, there is growing evidence that clopidogrel may cause thrombotic thrombocytopenic purpura/haemolytic uraemic syndrome (TTP/HUS). This association has been debated, since in several cases alternative causes could not be excluded. Two new cases of TTP/HUS associated with clopidogrel are reported here. After discontinuation of clopidogrel and treatment with plasma exchange, both patients had a complete and sustained recovery from TTP/HUS. These cases corroborate previous observations that clopidogrel may indeed be a rare cause of TTP/HUS.

Mannan-binding lectin in children with Escherichia coli O157:H7 haemmorrhagic colitis and haemolytic uraemic syndrome

Mannan-binding lectin (MBL) triggers complement activation upon binding to microbial surfaces. MBL deficiency has been associated with increased susceptibility to severe bacterial infections. We hypothesized that MBL deficiency may predispose children to Shiga toxin-producing Escherichia coli (STEC) O157:H7 infections and the associated haemolytic uraemic syndrome (HUS). We compared circulating levels of MBL among children with uncomplicated O157:H7 haemorrhagic colitis (HC), patients with O157:H7 HUS, normal and diseases control groups. Circulating MBL concentrations on admission were as follows: 3.22 +/- 2.43 micro g/ml among normal controls (n = 23); 2.90 +/- 2.44 micro g/ml in patients with rotavirus enteritis (n = 10); 2.78 +/- 1.65 micro g/ml in children with HC due to non-STEC bacterial pathogen (n = 15); 2.67 +/- 2.44 micro g/ml in patients with uncomplicated O157:H7 HC (n = 27); 2.80 +/- 2.97 micro g/ml in children with O157:H7 HUS (n = 15); 6.70 +/- 4.49 micro g/ml in patients with chronic renal failure unrelated to O157:H7 infection (n = 6). Higher MBL levels were found in patients with chronic renal failure compared to O157:H7 HC (P < 0.047). However, MBL concentrations <0.5 micro g/ml, which have been associated with MBL deficiency in relation to increased susceptibility to infections, were noted at comparable rates between the different groups (P = NS). Our data does not support that MBL deficiency may predispose to O157:H7 infections nor than the development of diarrhoea associated HUS.

Pretreatment of mice with lipopolysaccharide (LPS) or IL-1beta exerts dose-dependent opposite effects on Shiga toxin-2 lethality

Haemolytic uraemic syndrome (HUS) has been closely associated with infection with a group of Shiga toxin-producing enterohaemorrhagic Eschericchia coli in young children. Shiga toxins (Stx) have been implicated as pathogenic agents of HUS by binding to the surface receptor of endothelial cells. LPS is a central product of the Gram-negative bacteria and several reports have documented that both LPS and Stx are important for disease development. In this study the reciprocal interactions between LPS and Stx2 are analysed in a mouse model. The results demonstrated that LPS was able to reduce or enhance Stx2 toxicity, depending on the dose and the timing of the injection. The involvement of the main early cytokines induced by LPS, tumour necrosis factor alpha (TNF-alpha) and IL-1beta, in those LPS opposite effects on Stx2 toxicity was evaluated. Stx2 toxicity was enhanced by in vivo injection of murine TNF-alpha and low doses of murine IL-1beta. However, at higher doses of IL-1beta which induced corticosteroid increase in serum, Stx2 lethality was decreased. Considering that dexamethasone and IL-1beta reproduce the LPS protective effects, it is suggested that endogenous corticosteroids secondary to the inflammatory response induced by LPS, mediate the protection against Stx2. It can be concluded that the fine equilibrium between proinflammatory and anti-inflammatory activities strongly influences Stx2 toxicity.

Depletion of liver and splenic macrophages reduces the lethality of Shiga toxin-2 in a mouse model

The haemolytic uraemic syndrome (HUS) is a clinical syndrome consisting of haemolytic anaemia, thrombocytopenia, and acute renal insufficiency. HUS is the most frequent cause of acute renal failure in childhood. It has been previously suggested that the presence of Shiga toxin (Stx) is necessary but not sufficient for HUS development, and cytokines such as tumour necrosis factor-alpha (TNF-alpha) and IL-1beta appear to be necessary to develop the syndrome. Since the mononuclear phagocytic system (MPS) is the major source of these cytokines, macrophages might be one of the relevant targets for Stx action in the pathophysiology of HUS. In this study our objective was to examine the role of the hepatic and splenic macrophages in a mouse model of HUS induced by injection of Shiga toxin type-2 (Stx2) or Stx2 plus lipopolysaccharide (LPS). For this purpose, depletion of mice macrophages by liposome-encapsulated clodronate (lip-clod), followed by injection of STx2 or Stx2 plus LPS, was assayed. In this study we show that depletion of hepatic and splenic macrophages by clodronate treatment induces a survival of 50% in animals treated with Stx2 alone or in presence of LPS. This maximal effect was observed when lip-clod was injected 48-72 h before Stx2 injection. Biochemical and histological parameters show characteristics of the lesion produced by Stx2, discarding non-specific damage due to LPS or lip-clod. In addition, we determined that the toxic action of Stx2 is similar in BALB/c and N:NIH nude mice, indicating the T cell compartment is not involved in the Stx2 toxicity. Briefly, we demonstrate that macrophages play a central role in the pathophysiology of HUS, and that the systemic production of cytokines by liver and/or spleen is for Stx2 to manifest its full cytotoxic effect. In addition, the toxicity of Stx2 alone, or in presence of LPS, is independent of the T cell compartment.