Hemolytic Uremic Syndrome Research Articles

An expert discussion on the atypical hemolytic uremic syndrome nomenclature—identifying a road map to precision: a report of a National Kidney Foundation Working Group

The term atypical hemolytic uremic syndrome has been in use since the mid-1970s. It was initially used to describe the familial or sporadic form of hemolytic uremic syndrome as opposed to the epidemic, typical form of the disease. Over time, the atypical hemolytic uremic syndrome term has evolved into being used to refer to anything that is not Shiga toxin-associated hemolytic uremic syndrome. The term describes a heterogeneous group of diseases of disparate causes, a circumstance that makes defining disease-specific natural history and/or targeted treatment approaches challenging. A working group of specialty-specific experts in the thrombotic microangiopathies was convened to review the validity of this broad term in an era of swiftly advancing science and targeted therapeutics. A Delphi approach was used to define and interrogate some of the key issues related to the atypical hemolytic uremic syndrome nomenclature.

Severe complicated malaria caused by Plasmodium falciparum in a female traveler returning from Zanzibar

A 25-year-old female outpatient presenting with fever and micro-hematuria was treated for urinary tract infection. Her condition worsened over 3 days at home. After experiencing multiple falls caused by leg weakness and mental confusion, she was admitted to a hospital with high fever. Initial laboratory findings showed hemolytic anemia, pancytopenia, and acute kidney injury, suggesting hemolytic uremic syndrome. However, a detailed fever evaluation revealed her recent return from Afrika. This prompted amalaria test, which confirmed Plasmodium falciparum infection with 80 % parasitemia. Despite the quick reduction of parasitemia following treatment with intravenous administered artesunate and oral Artemether-Lumefantrine, her condition worsened, leading to a septic shock. This required renal replacement and kinetic ventilation therapy, as well as blood transfusions due to persistent hemolysis until the laboratory values normalized after 48 days post-admission. The evaluation of fever is often challenging, but most often a detailed patient history is key to early diagnosis and treatment preventing deathly outcomes in severe cases.

THE UTILITY OF THE NORMAL THIN SECTION SKIN BIOPSY IN THE ASSESSMENT OF SYSTEMIC/EXTRACUTANEOUS DISEASE

Diseases reflective of multiorgan vascular injury of diverse etiology, peripheral nerve disease, dysautonomia syndromes and intravascular lymphoma malignancies may potentially exhibit abnormalities on a normal skin biopsy that may be instrumental in establishing a diagnosis. A retrospective review of our data base was conducted to uncover cases where a normal skin biopsy was performed to rule in or out certain systemic diseases such as complement driven thrombotic microvascular disease including atypical hemolytic uremic syndrome, post transplant thrombotic microangiopathy, and severe/critical COVID-19, systemic capillary leak syndrome, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) intravascular B cell lymphoma, dysautonomia syndromes and mast cell activation syndrome. Immunohistochemical stains were conducted inclu C5b-9, CD56, MXA, B and T cell markers. There were expected patterns critical in establishing diagnosis based on evaluating certain parameters including assessing for increased C5b-9 microvascular deposition from the deltoid area(atypical hemolytic uremic syndrome, post-transplant thrombotic microangiopathy, catastrophic antiphospholipid antibody syndrome and severe/critical COVID-19), enhanced type I interferon signaling (systemic capillary leak syndrome), ultrastructural arteriopathic changes (CADASIL),lower extremity reduced cutaneous autonomic innervation (small fiber neuropathy and POTS), abdominal, thigh and buttock skin for the presence of intravascular lymphocytes on biopsy(intravascular B cell lymphoma), distinct structural changes in elastic fibers supportive of pseudoxanthoma elasticum and a higher than normal density of mast cells in the absence of other inflammatory cell types (mast cell activation syndrome). The skin is a critical window for understanding disease, a concept well exemplified by the myriad of diseases that can be suggested by the microscopic and or ultrastructural examination of clinically normal skin, hence establishing the normal skin biopsy as an important tool for understanding extracutaneous disease.

Eculizumab as Salvage Treatment for Thrombotic Microangiopathy After Lung Transplantation.

Thrombotic microangiopathy (TMA) is a rare complication after lung transplantation (LT) that has seldom been characterized in detail. Recent evidence has linked TMA other than primary atypical hemolytic uremic syndrome (aHUS) with hyperactivation of the complement alternative pathway. The focus of this investigation was to analyze the treatment response with eculizumab in TMA after LT. Case series where we have studied 11 patients with TMA after LT from 2 Spanish tertiary healthcare centers. Clinical data and response rates to eculizumab are provided. The main indication for lung transplant was chronic obstructive pulmonary disease (COPD) (36%) and most cases (82%) received bilateral LT. The median time to TMA diagnosis was 11.6 months (4.7-28.9) and the TMA trigger in the majority of cases (73%) was immunosuppressive drugs. Platelet and hemoglobin nadir were 58×103/µL (24-108) and 7.7g/dL (7.1-7.9), respectively. All cases presented acute kidney injury (AKI) with a median creatinine of 4mg/dL (3.2-4.8) and 54.5% required acute dialysis. Eculizumab was started after a median time of 8 days (6-14) with a median duration of 3 weeks (2-8). Complete TMA response was observed in 7 (63.6%) cases and hematologic response in 10 (90.9%). The time to hematologic and renal response was 23 days (13-29) and 28 days (14-46), respectively. TMA after LT is infrequent but potentially devastating. Our findings suggest that short cycles of eculizumab may be effective for severe TMA after LT.

Immunodeficiency: Complement disorders.

The complement system is an important component of innate and adaptive immunity that consists of three activation pathways. The classic complement pathway plays a role in humoral immunity, whereas the alternative and lectin pathways augment the innate response. Impairment, deficiency, or overactivation of any of the known 50 complement proteins may lead to increased susceptibility to infection with encapsulated organisms, autoimmunity, hereditary angioedema, or thrombosis, depending on the affected protein. Classic pathway defects result from deficiencies of complement proteins C1q, C1r, C1s, C2, and C4, and typically manifest with features of systemic lupus erythematosus and infections with encapsulated organisms. Alternative pathway defects due to deficiencies of factor B, factor D, and properdin may present with increased susceptibility to Neisseria infections. Lectin pathway defects, including Mannose-binding protein-associated serine protease 2 (MASP2) and ficolin 3, may be asymptomatic or lead to pyogenic infections and autoimmunity. Complement protein C3 is common to all pathways, deficiency of which predisposes patients to severe frequent infections and glomerulonephritis. Deficiencies in factor H and factor I, which regulate the alternative pathway, may lead to hemolytic uremic syndrome. Disseminated Neisseria infections result from terminal pathway defects (i.e., C5, C6, C7, C8, and C9). Diagnosis of complement deficiencies involves screening with functional assays (i.e., total complement activity [CH50], alternative complement pathway activity [AH50], enzyme-linked immunosorbent assay [ELISA]) followed by measurement of individual complement factors by immunoassay. Management of complement deficiencies requires a comprehensive and individualized approach with special attention to vaccination against encapsulated bacteria, consideration of prophylactic antibiotics, treatment of comorbid autoimmunity, and close surveillance.

Legionella Pneumophila Presenting as a Rare Cause of Acute Thrombocytopenia: A Case Report and Review of Literature.

Legionella pneumophila can cause a wide spectrum of clinical manifestations, ranging from a mild flu-like illness to fulminant multi-organ involvement, characterised by severe pneumonia, diarrhoea, encephalopathy, shock, hepatic dysfunction and renal failure. Very rarely, it can be associated with haematologic conditions such as thrombotic thrombocytopenic purpura (TTP), haemolytic uraemic syndrome (HUS) and immune thrombocytopenic purpura (ITP). We report a rare case of L. pneumophila causing ITP and review previously published cases of thrombocytopenia associated with Legionellosis in the literature. A 53-year-old male presented with fevers, chills, a productive cough and severe haemoptysis. Blood work was remarkable for leukocytosis, severe thrombocytopenia and hyponatraemia. Computed tomography (CT) imaging showed left lower lobe lung consolidation, and a peripheral blood smear showed giant platelets consistent with ITP. Legionella urine antigen testing returned positive. He was treated with intravenous immunoglobin, steroid taper and a ten-day course of azithromycin, which led to normalisation of his platelet count and resolution of the pneumonia. L. pneumophila can lead to complement-mediated destruction of platelets resulting in ITP. Antibodies against L. pneumophila can also cross-react with the enzyme ADAMTS13, inhibiting its function and resulting in TTP and HUS. Additionally, L. pneumophila can infect vascular endothelial cells causing their death and stimulating release of von Willebrand factor (vWF) multimers into the bloodstream, promoting thrombosis and platelet consumption. It is important for internists to consider L. pneumophila in the differential for any patient presenting with pneumonia and severe thrombocytopenia. Earlier detection and intervention can lead to prevention of critical bleeding and better outcomes. Legionella pneumophila is rarely associated with different haematologic disorders resulting in severe bleeding diathesis as well as thrombosis.It is important for internists to consider Legionella pneumophila in the differential diagnosis for any patient presenting with pneumonia and severe thrombocytopenia.Earlier detection and intervention can lead to prevention of critical bleeding and better outcomes.

Complex presentation of atypical hemolytic uremic syndrome: A case study

This case study discusses atypical hemolytic uremic syndrome (aHUS) in a 67-year-old female who presented with hypertension and hyperlipidemia 8 days after a suspected foodborne illness. Her initial presentation included acute respiratory and renal failure in which her condition required extensive re-warming, intubation, pressor or vasopressor therapy, continuous renal replacement therapy or hemodialysis, broad-spectrum antibiotic therapy, and blood and culture workups. Kidney function also showed signs of renal failure, metabolic acidosis, thrombocytopenia, and an elevated level of lactate dehydrogenase in the laboratory results. Radiological investigations demonstrated enteritis, colitis, and an ischemic infarct without hemorrhage. Multidisciplinary consultations achieved the importance and urgency of early diagnosis and treatment of aHUS to prevent irreversible organ damage. This case highlights the role of a timely diagnosis and interprofessional patient care in the treatment of severe aHUS.

Lipopolysaccharide Core Truncation in Invasive Escherichia coli O157:H7 ATCC 43895 Impairs Flagella and Curli Biosynthesis and Reduces Cell Invasion Ability.

Escherichia coli O157:H7 (E. coli O157) is known for causing severe foodborne illnesses such as hemorrhagic colitis and hemolytic uremic syndrome. Although E. coli O157 is typically regarded as an extracellular pathogen and a weak biofilm producer, some E. coli O157 strains, including a clinical strain ATCC 43895, exhibit a notable ability to invade bovine crypt cells and other epithelial cells, as well as to form robust biofilm. This invasive strain persists in the bovine host significantly longer than non-invasive strains. Various surface-associated factors, including lipopolysaccharides (LPS), flagella, and other adhesins, likely contribute to this enhanced invasiveness and biofilm formation. In this study, we constructed a series of LPS-core deletion mutations (waaI, waaG, waaF, and waaC) in E. coli O157 ATCC 43895, resulting in stepwise truncations of the LPS. This approach enabled us to investigate the effects on the biosynthesis of key surface factors, such as flagella and curli, and the ability of this invasive strain to invade host cells. We confirmed the LPS structure and found that all LPS-core mutants failed to form biofilms, highlighting the crucial role of core oligosaccharides in biofilm formation. Additionally, the LPS inner-core mutants ΔwaaF and ΔwaaC lost the ability to produce flagella and curli. Furthermore, these inner-core mutants exhibited a dramatic reduction in adherence to and invasion of epithelial cells (MAC-T), showing an approximately 100-fold decrease in cell invasion compared with the outer-core mutants (waaI and waaG) and the wild type. These findings underscore the critical role of LPS-core truncation in impairing flagella and curli biosynthesis, thereby reducing the invasion capability of E. coli O157 ATCC 43895.

The Phenomenon of Thrombotic Microangiopathy in Cancer Patients.

Thrombotic microangiopathy (TMA) encompasses a range of disorders characterized by blood clotting in small blood vessels, leading to organ damage. It can manifest as various syndromes, including thrombotic thrombocytopenic purpura (TTP), hemolytic-uremic syndrome (HUS), and others, each with distinct causes and pathophysiology. Thrombo-inflammation plays a significant role in TMA pathogenesis: inflammatory mediators induce endothelial injury and activation of platelet and coagulation cascade, contributing to microvascular thrombosis. Primary TMA, such as TTP, is primarily caused by deficient ADAMTS13 metalloproteinase activity, either due to antibody-mediated inhibition or intrinsic enzyme synthesis defects. In cancer patients, a significant reduction in ADAMTS13 levels and a corresponding increase in VWF levels is observed. Chemotherapy further decreased ADAMTS13 levels and increased VWF levels, leading to an elevated VWF/ADAMTS13 ratio and increased thrombotic risk. Drug-induced TMA (DITMA) can result from immune-mediated or non-immune-mediated mechanisms. Severe cases of COVID-19 may lead to a convergence of syndromes, including disseminated intravascular coagulation (DIC), systemic inflammatory response syndrome (SIRS), and TMA. Treatment of TMA involves identifying the underlying cause, implementing therapies to inhibit complement activation, and providing supportive care to manage complications. Plasmapheresis may be beneficial in conditions like TTP. Prompt diagnosis and treatment are crucial to prevent serious complications and improve outcomes.

Enterohemorrhagic Escherichia coli (EHEC) disrupts intestinal barrier integrity in translational canine stem cell-derived monolayers.

This study develops a new model to better understand Enterohemorrhagic E. coli (EHEC) infections, a serious bacterial disease affecting both dogs and humans, characterized by symptoms such as hemorrhagic diarrhea and hemolytic uremic syndrome. Traditional research models have fallen short of mimicking how this disease manifests in patients. Our research used intestinal tissues from healthy dogs to create layers of cells, known as colonoid-derived monolayers, which we then exposed to EHEC. We assessed the damage caused by the bacteria using several techniques, observing significant changes similar to those seen in actual cases of the disease. The model proved effective in replicating the interaction between the host and the pathogen, marking an important step toward understanding EHEC's effects and developing treatments. This canine colonoid-derived monolayer system not only bridges a crucial gap in current research but also offers a promising platform for studying other enteric pathogens affecting both canine and human health.

Long-Term Outcomes of Anticomplement Factor H Antibody Positive Versus Negative Atypical Hemolytic Uremic Syndrome

Background Atypical hemolytic uremic syndrome (aHUS) is a severe thrombotic microangiopathy predominantly affecting the kidneys, often associated with complement dysregulation. This study is aimed to analyze the clinical characteristics, treatment outcomes, and long-term implications of aHUS in a resource-limited setting. Materials and Methods A retrospective observational study conducted at an institute between January 2016 and December 2022 included all patients with aHUS, excluding secondary causes and renal transplant recipients. Demographic profiles, clinical features, laboratory parameters, treatment modalities (immunosuppression and plasma exchange), and outcomes were collected. Anticomplement Factor H (anti-CFH) antibody, complement levels, and genetic mutation analysis were performed to ascertain etiological factors. The patient and renal outcomes of anti-CFH positive and negative patients on long-term follow-up were compared. Results Fifty-seven patients (mean age: 12.5 ± 4.9 years; 63% males) were analyzed. Among them, 33 (57.9%) tested positive for anti-CFH antibodies and eight presented postpartum. Initial remission was achieved in 42 (73.6%) patients, with 13 (22.8%) partial and 29 (50.9%) complete remission. The median follow-up duration was 24 months [interquartile range (IQR) 8.5–84]; 12 (21%) patients died, with two deaths during the index admission, six among nonresponders, and 4 among responders. Dialysis-free renal survival was superior in anti-CFH seropositive patients (81.2%) compared to seronegative counterparts (55.9%), while patient survival was statistically similar between the two groups. Elevated anti-CFH titers (>4000 AU/ml), age ≥16 years, female gender, and seizures predicted nonresponsiveness. Conclusion Anti-CFH antibody associated aHUS had better kidney outcomes than the seronegative counterparts. In resource limited settings, a combination of plasma exchange and immunosuppression showed promising results in the short and long term.

Postpartum Renal Cortical Necrosis: A Case Series

Rationale & ObjectivePostpartum renal cortical necrosis (postpartum RCN) is a severe form of obstetric acute kidney injury. This study aimed to identify clinicopathological features in Chinese postpartum RCN cases to determine how pathologic findings may contribute to the treatment and prognosis. Study DesignSingle-center, case series Setting & ParticipantsTwelve patients with postpartum RCN had kidney biopsies at Peking University First Hospital between 2014 and 2021. The diagnosis of postpartum RCN was made according to typical MRI or pathological features. Clinical, laboratory and pathological data were compared between patients with eGFR <30 (poor outcome) and ≥30 ml/min/1.73 m2 after six months. ObservationsAll postpartum RCN patients presented with stage 3 AKI attributed to a probable atypical hemolytic uremic syndrome. Pregnancy terminations occurred at a median gestational age of 35.5 weeks. Kidney biopsy was performed ranging 18 days to 4 months from delivery. Upon biopsy, hemoglobin, platelet count and LDH levels had been restored to 137 g/L, 214 ×109/L and 231.50±65.01 U/L, respectively. Four patients exhibited poor outcome, demonstrating higher schistocyte count, serum creatinine and mean arterial pressure at onset. Pathologically, glomerular segmental sclerosis was prevalent. The NOS variant was the most common type, followed by collapsing variant, cellular variant, and tip variant. Patients with poor kidney outcome had more glomerular coagulative necrosis, capillary thrombosis, extensive cortical coagulative necrosis, and pronounced arteriole/artery lesions including increased interlobular arteriole intimal edema and fibrin thrombosis, but a lower occurrence of segmental sclerosis. LimitationsLimited sample size and retrospective design. ConclusionsOur research has identified key pathological features in postpartum RCN patients with aHUS, highlighting the necessity for more effective therapeutic options. There is a clear demand for non-invasive biomarkers that can accurately track disease progression and inform treatment duration for long-term outcomes improvement.

Recent data on atypical hemolytic uremic syndrome associated with pregnancy, kidney transplantation or hypertensive emergency

Les microangiopathies thrombotiques (MAT) sont un groupe hétérogène de pathologies caractérisées à différents degrés par une anémie hémolytique mécanique, une thrombopénie et une occlusion microvasculaire histologique. Les MAT peuvent se compliquer de multiples atteintes d’organe, principalement neurologiques et néphrologiques (définissant alors le syndrome hémolytique et urémique). La classification fondée sur la physiopathologie de la maladie a mis en évidence l’importance de la dérégulation de la voie alterne du complément dans les SHU atypiques (SHUa) (non-liés aux infections). Cependant, la physiopathologie et le traitement de nombreuses formes de SHUa dans des contextes spécifiques (tels que la grossesse, la transplantation rénale ou l’urgence hypertensive) restent mal caractérisés. Dans cet article, nous reprenons les avancées diagnostiques et thérapeutiques récentes dans ces trois formes de SHUa aux contextes spécifiques. Nous montrons les spécificités de ces formes et décrivons les enjeux actuels et futurs de leur prise en charge.

Генетически-фенотипический профиль детей с атипичным гемолитико-уремическим синдромом

Atypical hemolytic uremic syndrome (aHUS) is a life-threatening disease caused by dysregulation of the alternative complement pathway as a result of mutations in complement genes or the formation of antibodies (AB) to some of the complement factors. Identification of the gene mutations incidence and the corresponding phenotypic features in pediatric patients with aHUS in Russia is aimed at improving the diagnosis and prognosis of the disease as well as treatment tactics planning for patient management. The purpose of this research was to determine the patterns of progression, prognosis and outcomes of aHUS in children depending on their genetic profile. Materials and methods used: the Article represents data from a retro- and prospective analyses of the characteristics of the course of aHUS in 172 children depending on their genetic profile performed in Jan. 2012-Feb. 2022. The sporadic form of aHUS was diagnosed after exclusion of the other forms of thrombotic microangiopathy (TMA), the familial form (in cases with the familial records), the acquired (CFH-Ab HUS) in cases with AB increase to factor H. AutoAb against factor H was determined by enzyme-linked immunosorbent assay (ELISA-VIDITEST anti-complement factor H). The search for mutations (n=167) was carried out using Next-generation Sequencing (NGS) and Sanger sequencing methods. Results: the sporadic form of aHUS was diagnosed in 96.9% of cases, familial in 3.1% and CFH-Ab HUS in 23.8%. The genetic nature of aHUS was confirmed in 53.4% of cases. Pathogenic mutations were detected in 8.6% of cases, probably pathogenic in 42.8% and those with unclear clinical significance in 46.8%. The complement genes mutations were detected in 88.5% of cases and mutations of genes not related to the complement system (ADAMTS13, DGKE, INF2) in 11.5%. The most frequently identified mutations were in the CFH (17.1%), C3 (12.9%) and CD46 (12.9%) genes and less frequently in CFI (7.1%), THBD (5.7%), CFHR5 (5.7%) and CFB (1.4%). In children with CFH-Ab HUS, the CFHR1/CFHR3 deletion was detected in 87.8% of cases, including in 19.4% in combination with mutations of unknown clinical significance. Multiple organ failure syndrome had developed in 77.8% of cases in children with pathogenic/probably pathogenic mutations, in 85.3% in patients with mutations of unknown clinical significance, in 91.8% in patients without mutations and in 83.3% in patients with CFHR1/CFHR3 deletion. Chronic kidney disease (CKD) stages 3 to 5 in sporadic/familial aHUS, regardless of genetic profile, had counted for 14.5% and 16.7% in CFH-Ab HUS. Lethal outcome occurred in 4.3% of cases in the presence of mutations, in 4.9% in the absence of mutations and in 2.8% in cases of CFHR1/CFHR3 deletion. Relapses of aHUS prior to the Eculizumab treatment had developed more often in the presence of CFHR1/CFHR3 mutations and deletion in comparison with children without mutations (31.4% v. 13.1%, p=0.0313 and 44.4% v. 13.1%, p= 0.004). Relapse of aHUS after discontinuation of the Eculizumab therapy had developed in 16.4% of cases. Risk factors for the relapse of aHUS were as follows: patient’s age above 12 months old at the time of the development of aHUS, severe arterial hypertension in the acute period, the use of Eculizumab at the fourth week after the onset of the disease and/or later, recurrent course of aHUS and the presence of CKD prior to the start of the Eculizumab therapy. Conclusion: The genetic profile of patients does not determine the severity and outcome of aHUS though it does affect the relapse rate. The prognosis and survival of patients with aHUS are determined by the severity of the acute period and the timeliness of the complement blocking therapy management.

A rapid on-site loop-mediated isothermal amplification technology as an early warning system for the detection of Shiga toxin-producing Escherichia coli in water.

Shiga toxin-producing Escherichia coli (STEC) is an important waterborne pathogen capable of causing serious gastrointestinal infections with potentially fatal complications, including haemolytic-uremic syndrome. All STEC serogroups harbour genes that encode at least one Shiga toxin (stx1 and/or stx2), which constitute the primary virulence factors of STEC. Loop-mediated isothermal amplification (LAMP) enables rapid real-time pathogen detection with a high degree of specificity and sensitivity. The aim of this study was to develop and validate an on-site portable diagnostics workstation employing LAMP technology to permit rapid real-time STEC detection in environmental water samples. Water samples (n=28) were collected from groundwater wells (n=13), rivers (n=12), a turlough (n=2) and an agricultural drain (n=1) from the Corrib catchment in Galway. Water samples (100 ml) were passed through a 0.22 µm filter, and buffer was added to elute captured cells. Following filtration, eluates were tested directly using LAMP assays targeting stx1, stx2 and E. coli phoA genes. The portable diagnostics workstation was used in field studies to demonstrate the on-site testing capabilities of the instrument. Real-time PCR assays targeting stx1 and stx2 genes were used to confirm the results. The limit of detection for stx1, stx2 and phoA LAMP assays were 2, 2 and 6 copies, respectively. Overall, stx1, stx2 and phoA genes were detected by LAMP in 15/28 (53.6 %), 9/28 (32.2 %) and 24/28 (85.7 %) samples, respectively. For confirmation, the LAMP results for stx1 and stx2 correlated perfectly (100 %) with those obtained using PCR. The portable diagnostics workstation exhibited high sensitivity throughout the on-site operation, and the average time from sample collection to final result was 40 min. We describe a simple, transferable and efficient diagnostic technology for on-site molecular analysis of various water sources. This method allows on-site testing of drinking water, enabling evidence-based decision-making by public health and water management authorities.

Diversity of Shiga toxin transducing phages in Escherichia coli O145:H28 and the different Shiga toxin 2 production levels associated with short- or long-tailed phages.

Shiga toxin (Stx)-producing Escherichia coli (STEC) causes serious gastrointestinal illness, including hemorrhagic colitis and hemolytic uremic syndrome. Two types of Stxs (Stx1 and Stx2) are known and both are encoded by bacteriophages (Stx phages), but the production of Stx2 is known to be a major risk factor for severe STEC infections. The production of Stx2, but not Stx1, is tightly coupled with the induction of Stx phages, and Stx2 production levels vary between STEC strains even within the same serotype. Here, we analyzed the genomic diversity of all Stx phages in 71 strains representing the entire O145:H28 lineage, one of the often highly pathogenic STECs, and the relationship between the variations in Stx phage genomes and the levels of Stx2 production by host strains. Our analysis reveals highly dynamic natures of Stx phages in O145:H28, including the independent acquisition of similar Stx phages by different sublineages, the recent transfer of Stx phage between different sublineages, and the frequent gain and loss of Stx phages in some sublineages. We also show the association of the Stx2 phage types with the Stx2 production levels of host strains: strains carrying short-tailed Stx2 phages exhibited significantly higher Stx2 production levels than those carrying long-tailed Stx2 phages. Detailed analyses of the Stx2 phage genomes revealed that both of short- and long-tailed phages exhibited sequence diversification and they were divided into two groups, respectively, based on the sequence similarity of the phage early region encoding genes responsible for phage induction, short-tailed phages contained early regions clearly different in genetic organization from those in long-tailed phages. Therefore, the variations in the early regions between short-and long-tailed Stx2 phages appeared to be linked to a striking difference in Stx2 production levels in their host strains. These results broaden our understanding of the diversification and dynamism of Stx phages in O145:H28 and the association of Stx2 phage types with the Stx2 production level in this STEC lineage.

Annual trends in atypical haemolytic uremic syndrome management in Japan and factors influencing early diagnosis and treatment: a retrospective study

Atypical haemolytic uremic syndrome (aHUS) is a rare disorder characterised by complement-mediated thrombotic microangiopathy (TMA). Despite clinical guidelines, the diagnosis and treatment of aHUS in its early stages remains challenging. This study examined the annual trends in aHUS clinical practices in Japan and explored factors influencing early diagnosis and treatment. Using data from the 2011–2020 Diagnosis Procedure Combination database, 3096 cases with the HUS disease code were identified, of which 217 were confirmed as aHUS and treated with eculizumab or plasma exchange. Early initiation, defined as starting eculizumab or plasma exchange within 7 days of admission, was the focus of the study. Our study revealed no significant changes over time in the number of aHUS diagnoses, cases treated with eculizumab, or early initiation cases. Early initiation cases underwent haemodialysis earlier and had ADAMTS13 activity measured earlier, shorter hospital stays, and lower hospitalisation costs than late initiation cases. In conclusion, we found no increase in the number of newly diagnosed aHUS cases or early treatment initiation over time. Early recognition of TMA and differentiation of the causative disease are crucial for identifying potential aHUS cases, which may lead to better patient prognoses.

Protein-losing enteropathy as a new phenotype in atypical hemolytic uremic syndrome caused by CD46 gene mutation.

Atypical hemolytic uremic syndrome (aHUS) is a life-threatening thrombotic microangiopathy. Genetic defects in the alternative complement (AP) pathway have been identified in 60-70% of individuals. Eculizumab is recommended as a first-line therapy. We collected the clinical data of a pediatric patient with aHUS accompanied by protein-losing enteropathy (PLE). Genetic testing was performed. Related literature on aHUS combined with PLE was reviewed. A 15-year-old Chinese girl was diagnosed with aHUS at 3.7years of age and experienced five episodes; her symptoms completely resolved with plasma treatment. Severe gastrointestinal symptoms and hypoalbuminemia presented after the first episode, and PLE was diagnosed. A novel homozygous CD46 variant was identified, and FACS revealed significantly decreased CD46 expression. She presented at a recent relapse with persistent GI symptoms and headache and progressed to chronic kidney failure; peritoneal dialysis was initiated. Eculizumab was given 8months after the last recurrence. Surprisingly, PLE was cured. Afterward, dialysis was discontinued, and eGFR recovered to 44.8ml/min/1.73 m2. A review of the literature indicated that PLE with thrombosis was caused by CD55 variants via hyperactivation of the AP system. We report an aHUS patient with PLE caused by CD46 variants. Symptoms of both PLE and aHUS were significantly alleviated in our patient and patients with CD55 variants treated with eculizumab, indicating that PLE was a new symptom of aHUS in our patient with a CD46 variant. Our case expands the phenotype of aHUS caused by a CD46 mutation and provides evidence of the efficacy of eculizumab after a long phase of chronic kidney failure.

In situ deposition of nanobodies by an engineered commensal microbe promotes survival in a mouse model of enterohemorrhagic E. coli.

Engineered smart microbes that deliver therapeutic payloads are emerging as treatment modalities, particularly for diseases with links to the gastrointestinal tract. Enterohemorrhagic E coli (EHEC) is a causative agent of potentially lethal hemolytic uremic syndrome. Given concerns that antibiotic treatment increases EHEC production of Shiga toxin (Stx), which is responsible for systemic disease, novel remedies are needed. EHEC encodes a type III secretion system (T3SS) that injects Tir into enterocytes. Tir inserts into the host cell membrane, exposing an extracellular domain that subsequently binds intimin, one of its outer membrane proteins, triggering the formation of attaching and effacing (A/E) lesions that promote EHEC mucosal colonization. Citrobacter rodentium (Cr), a natural A/E mouse pathogen, similarly requires Tir and intimin for its pathogenesis. Mice infected with Cr(ΦStx2dact), a variant lysogenized with an EHEC-derived phage that produces Stx2dact, develop intestinal A/E lesions and toxin-dependent disease. Stx2a is more closely associated with human disease. By developing an efficient approach to seamlessly modify the C. rodentium genome, we generated Cr_Tir-MEHEC(ΦStx2a), a variant that expresses Stx2a and the EHEC extracellular Tir domain. We found that mouse pre-colonization with HS-PROT3EcT-TD4, a human commensal E. coli strain (E. coli HS) engineered to efficiently secrete- an anti-EHEC Tir nanobody, delayed bacterial colonization and improved survival after challenge with Cr_Tir-MEHEC(ΦStx2a). This study provides the first evidence to support the efficacy of engineered commensal E. coli to intestinally deliver therapeutic payloads that block essential enteric pathogen virulence determinants, a strategy that may serve as an antibiotic-independent antibacterial therapeutic modality.

Two cases of typical HUS in adults treated with an anti-C5 monoclonal antibody: a new perspective?

Hemolytic uremic syndrome (HUS) is a rare clinical entity, especially in adults. In its typical form the causative factor that triggers the cascade of immunologic and inflammatory events is a Shiga toxin-producing pathogen, found in the patient's stool. Renal and neurologic involvement usually prevails and requires immediatecare. Regarding thispotentially life-threatening condition, little is known and the mainstay is supportive care. However, some interesting evidence has come up about the use of eculizumab, an anti-C5 monoclonal antibody, mainly in pediatric patients with typical HUS. Herein, we present two cases with typical HUS caused by two different strains of Escherichia coli (Shiga toxin-producing enterohemorrhagic and enteropathogenic) who were both treated effectively with anti-C5 monoclonal antibodies (eculizumab and ravulizumab).