RARE DISEASE
Infection-related hemolytic uremic syndrome
Infection-related hemolytic uremic syndrome
Infection-related hemolytic uremic syndrome
Synonyms: Infection-related HUS
Synonyms: Infection-related HUS
Synonyms: Infection-related HUS
Drug discovery
3
drugs
With orphan designations
Overview
Infection-related hemolytic uremic syndrome (HUS) is a thrombotic microangiopathy characterized by hemolytic anemia, thrombocytopenia, and acute kidney injury. It most commonly follows Shiga toxin-producing E. coli (STEC) infections, manifesting after bloody diarrhea. While predominantly affecting children, it can occur in adults with comorbidities. Management prioritizes supportive care, as antibiotics may exacerbate toxin release. Despite acute mortality rates <5%, 25% experience chronic kidney impairment, highlighting its significant healthcare burden [1][4][9][12].
Population
Children <5 years account for 75% of cases, with peak incidence 1-3/100,000 annually [2][4][12].
Adults with immunodeficiency, pregnancy, or chronic conditions face higher complication risks [7][11][17].
Seasonal clusters linked to contaminated food/water outbreaks, particularly June-September [2][7].
Therapies
Supportive care: IV rehydration, renal replacement therapy (50-60% require dialysis), and packed RBC transfusions [3][6][13].
Avoidance of antibiotics/antimotility agents during diarrheal phase due to increased toxin release [3][8][16].
Emerging therapies: Eculizumab considered in refractory cases despite limited evidence for STEC-HUS [3][8][14].
Categories: rare hematological diseases, rare renal diseases, rare transplant-related disorders
Research Papers
34 drug discovery papers about Infection-related hemolytic uremic syndrome, with 4 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
34 drug discovery papers about Infection-related hemolytic uremic syndrome, with 4 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
categories:
Small molecules
antibodies
2026-09-11 | Shiga Toxin-Producing Escherichia coli in Animal Reservoirs, Serotype Diversity, Virulence Profiles, and Antimicrobial Resistance Trends (2020–2026): A Scoping Review
Background/Objectives: Shiga toxin-producing Escherichia coli (STEC) are important zoonotic pathogens associated with gastrointestinal infections and hemolytic–uremic syndrome (HUS). Increasing serotype diversity, emergence of hybrid strains, and growing antimicrobial resistance complicate surveillance and treatment. This review summarizes recent data on STEC isolated from major animal reservoirs between 2020 and 2026. Methods: We comparatively analyzed peer-reviewed, open-access studies investigating STEC from cattle, sheep, goats, poultry, wildlife, and related animal products. We extracted and evaluated data on serotypes, virulence genes, hybrid pathotypes, and antimicrobial resistance determinants. Results: High serotype diversity was observed across all reservoirs, with non-O157 STEC frequently predominating over O157:H7. Ruminant isolates commonly carried stx2 and additional virulence determinants associated with severe human disease, confirming cattle and small ruminants as major reservoirs of highly pathogenic STEC. Poultry-associated isolates showed greater variability in virulence profiles but frequently exhibited high rates of multidrug resistance. Hybrid strains combining virulence traits characteristic of multiple E. coli pathotypes were increasingly reported. Livestock-associated STEC commonly carried resistance determinants against β-lactams, tetracyclines, sulfonamides, quinolones, and polymyxins, whereas wildlife isolates generally showed lower rates of resistance. Conclusions: Animal-associated STEC populations demonstrate increasing genomic diversity, pathogenic potential, and antimicrobial resistance. The growing prevalence of non-O157 and hybrid strains highlights the limitations of traditional serotype-focused surveillance and emphasizes the need for integrated One Health monitoring strategies.
2025-12-01 | ATYPICAL HEMOLYTIC UREMIC SYNDROME: FROM PATHOPHYSIOLOGY TO THERAPEUTIC ADVANCES
Atypical hemolytic uremic syndrome (aHUS) is a rare, life-threatening thrombotic microangiopathy (TMA) distinct from Shiga toxin-producing Escherichia coli (STEC)-related HUS. It is primarily driven by genetic or acquired dysregulation of the complement system, with pathogenic variants in complement factor H (CFH), factor I (CFI), membrane cofactor protein (MCP/CD46), factor B (CFB), and C3 identified in nearly 60% of patients. The resulting uncontrolled activation of the alternative complement pathway leads to endothelial damage, platelet activation, and microvascular thrombosis, most prominently affecting renal function. Clinically, aHUS is characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia, and organ injury, most commonly renal but often involving extra-renal systems such as cardiovascular, neurological, dermatological, and gastrointestinal organs. Diagnosis is challenging, requiring exclusion of other TMAs such as thrombotic thrombocytopenic purpura (TTP) and typical HUS. Early and accurate identification is essential to prevent irreversible organ damage. Diagnostic workup integrates clinical, laboratory, and genetic testing. ADAMTS13 activity measurement is critical to exclude TTP, while Shiga toxin assays help differentiate typical HUS. Complement biomarkers, including soluble C5b-9 and factor Ba, are under investigation for their diagnostic and prognostic utility. Genetic testing, employing next-generation sequencing and MLPA, provides prognostic insights and guides therapy, though penetrance remains incomplete and environmental triggers (infections, pregnancy, transplantation) play a pivotal role. Therapeutically, plasma exchange was historically the first-line option, but outcomes were poor with high rates of end-stage renal disease (ESRD). The advent of complement inhibitors has revolutionized management. Eculizumab, a monoclonal antibody targeting C5, effectively halts terminal complement activation, resulting in rapid hematologic normalization and renal recovery, especially when initiated early. Ravulizumab, a long-acting C5 inhibitor requiring infusions every 8 weeks, offers comparable efficacy with improved quality of life. Real-world studies confirm their sustained safety and effectiveness, though concerns regarding meningococcal infections necessitate vaccination and antibiotic prophylaxis. The duration of therapy remains debated; relapse occurs in 20–30% after discontinuation, particularly in carriers of CFH and CFI mutations. Emerging biomarkers and genetic stratification may enable more personalized discontinuation strategies. Despite therapeutic advances, significant challenges remain. Complement inhibitors impose a lifelong economic burden, raising questions of cost-effectiveness and accessibility. Health-economic analyses highlight the need for balanced strategies between clinical benefit and financial sustainability. Furthermore, gaps persist in standardized diagnostic criteria, access to genetic testing, and long-term outcome data for ravulizumab. Ongoing research focuses on refining biomarkers for risk stratification, identifying novel complement targets, and developing more affordable therapies. Special considerations arise in pregnancy-associated aHUS, post-transplant recurrence, and pediatric populations, where individualized management is critical. In conclusion, aHUS exemplifies a paradigm shift in the treatment of rare complement-mediated diseases. Early recognition, integration of genomic data, and targeted complement inhibition have transformed its prognosis. Future research must focus on optimizing therapeutic duration, expanding access to novel agents, and achieving a cost-effective, precision medicine approach for this devastating disorder.
2025-11-05 | Case Report: Effective use of eculizumab in treating recurrent atypical HUS following renal transplantation triggered by SARS-CoV-2 infection
Atypical hemolytic uremic syndrome (aHUS) is a severe post-transplant complication associated with a high risk of graft loss and mortality. Based on its pathophysiological mechanism, aHUS can be classified into recurrent aHUS (reactivation post-transplantation) and de novo aHUS (new-onset disease after transplantation). This study reports a case of a 52-year-old kidney transplant recipient who developed recurrent aHUS 10 months post-transplantation, triggered by SARS-CoV-2 infection. Genetic analysis revealed mutations in complement-related genes CFHR and C3. Following the diagnosis, the patient received a course of eculizumab induction therapy (900 mg/week for the first 4 weeks), followed by long-term maintenance therapy (900 mg every 2 weeks). Significant clinical improvement was observed, including stabilization of blood pressure, normalization of hemoglobin and lactate dehydrogenase (LDH) levels, an increase in platelet count, and a urine output exceeding 2,000 mL per day. The patient continued regular follow-up after discharge, with stable graft function. This case highlights the potential role of SARS-CoV-2 and other infections as triggers for aHUS recurrence in kidney transplant recipients and further supports the efficacy of eculizumab in treating recurrent aHUS. Furthermore, this study underscores the importance of precise immune risk stratification and early intervention in the effective management of aHUS recurrence.
2025-11-05 | Data Sheet 1_Case Report: Effective use of eculizumab in treating recurrent atypical HUS following renal transplantation triggered by SARS-CoV-2 infection.docx
Atypical hemolytic uremic syndrome (aHUS) is a severe post-transplant complication associated with a high risk of graft loss and mortality. Based on its pathophysiological mechanism, aHUS can be classified into recurrent aHUS (reactivation post-transplantation) and de novo aHUS (new-onset disease after transplantation). This study reports a case of a 52-year-old kidney transplant recipient who developed recurrent aHUS 10 months post-transplantation, triggered by SARS-CoV-2 infection. Genetic analysis revealed mutations in complement-related genes CFHR and C3. Following the diagnosis, the patient received a course of eculizumab induction therapy (900 mg/week for the first 4 weeks), followed by long-term maintenance therapy (900 mg every 2 weeks). Significant clinical improvement was observed, including stabilization of blood pressure, normalization of hemoglobin and lactate dehydrogenase (LDH) levels, an increase in platelet count, and a urine output exceeding 2,000 mL per day. The patient continued regular follow-up after discharge, with stable graft function. This case highlights the potential role of SARS-CoV-2 and other infections as triggers for aHUS recurrence in kidney transplant recipients and further supports the efficacy of eculizumab in treating recurrent aHUS. Furthermore, this study underscores the importance of precise immune risk stratification and early intervention in the effective management of aHUS recurrence.
2025-10-16 | Extracorporeal Membrane Oxygenation and Eculizumab for Cardiac Failure in STEC-HUS
Hemolytic uremic syndrome (HUS) is a complication of Shiga toxin-producing Escherichia coli (STEC) infection that can cause acute renal failure and introduce serious extrarenal organ injury. The most life threatening of these include cardiac failure and thrombocytopenia. Here, we present a case of severe STEC-HUS in a previously healthy 2-year-old boy who progressed to cardiac failure necessitating extracorporeal membrane oxygenation (ECMO). Following ECMO cannulation, he was treated with eculizumab, an anticomplement component 5 monoclonal antibody. The patient required ECMO for 5 days and subsequently survived decannulation with normal cardiac function and a good neurological outcome. This case illustrates the feasibility of ECMO despite the consumptive thrombocytopenia characteristic of HUS as well as the potential role of eculizumab in facilitating cardiac recovery. Additionally, we propose anticoagulation parameters balancing HUS-related thrombocytopenia with hemorrhagic complications while on ECMO. Further studies are warranted to better understand complement dysregulation in the pathophysiology of STEC-HUS and develop treatment guidelines for STEC-HUS with cardiac manifestations.
vaccines
2025-08-13 | In Silico Design of a Multiepitope Vaccine Against Intestinal Pathogenic Escherichia coli Based on the 2011 German O104:H4 Outbreak Strain Using Reverse Vaccinology and an Immunoinformatic Approach
Background: While most Escherichia coli strains are harmless members of the gastrointestinal microbiota, certain pathogenic variants can cause severe intestinal and extraintestinal diseases. A notable outbreak of E. coli O104:H4, involving both enteroaggregative (EAEC) and enterohemorrhagic (EHEC) strains, occurred in Europe, resulting in symptoms ranging from bloody diarrhea to life-threatening colitis and hemolytic uremic syndrome (HUS). Since treatment options remain limited and have changed little over the past 40 years, there is an urgent need for an effective vaccine. Such a vaccine would offer major public health and economic benefits by preventing severe infections and reducing outbreak-related costs. A multiepitope vaccine approach, enabled by advances in immunoinformatics, offers a promising strategy for targeting HUS-causing E. coli (O104:H4 and O157:H7 serotypes) with minimal disruption to normal microbiota. This study aimed to design an immunogenic multiepitope vaccine (MEV) construct using bioinformatics and immunoinformatic tools. Methods and Results: Comparative proteomic analysis identified 672 proteins unique to E. coli O104:H4, excluding proteins shared with the nonpathogenic E. coli K-12-MG1655 strain and those shorter than 100 amino acids. Subcellular localization (P-SORTb) identified 17 extracellular or outer membrane proteins. Four proteins were selected as vaccine candidates based on transmembrane domains (TMHMM), antigenicity (VaxiJen), and conservation among EHEC strains. Epitope prediction revealed ten B-cell, four cytotoxic T-cell, and three helper T-cell epitopes. Four MEVs with different adjuvants were designed and assessed for solubility, stability, and antigenicity. Structural refinement (GALAXY) and docking studies confirmed strong interaction with Toll-Like Receptor 4 (TLR4). In silico immune simulations (C-ImmSim) indicated robust humoral and cellular immune responses. In Conclusions, the proposed MEV construct demonstrated promising immunogenicity and warrants further validation in experimental models.
2023-02-01 | The role of pneumococcal extracellular vesicles on the pathophysiology of the kidney disease Hemolytic Uremic Syndrome
Abstract Streptococcus pneumoniae -induced hemolytic uremic syndrome (Sp-HUS) is a kidney disease characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. This disease is frequently underdiagnosed and its pathophysiology is poorly understood. In this work, we compared clinical strains, isolated from infant Sp-HUS patients, to a reference pathogenic strain D39, for host cytotoxicity and further explored the role of Sp-derived extracellular vesicles (EVs) in the pathogenesis of a HUS infection. In comparison with the WT strain, pneumococcal HUS strains caused significant lysis of human erythrocytes and increased the release of hydrogen peroxide. Isolated Sp-HUS EVs were characterized by performing dynamic light-scattering microscopy and proteomic analysis. Sp-HUS strain released EVs at a constant concentration during growth, yet the size of the EVs varied and several subpopulations emerged at later time points. The cargo of the Sp-HUS EVs included several virulence factors at high abundance, i.e., the ribosomal subunit assembly factor BipA, the Pneumococcal Surface Protein A (PspA), the lytic enzyme LytC, several sugar utilization and fatty acid synthesis proteins. Sp-HUS EVs strongly downregulated the expression of the endothelial surface marker PECAM-1 and were internalized by human endothelial cells. Sp-HUS EVs elicited the release of pro-inflammatory cytokines (IL-1ß, IL-6) and chemokines (CCL2, CCL3, CXCL1) by human monocytes. These findings shed new light on the overall function of Sp-EVs, in the scope of infection-mediated HUS, and suggest new avenues of research for exploring the usefulness of Sp-EVs as therapeutic and diagnostic targets. Importance Streptococcus pneumoniae is a life-threatening human pathogen associated with severe illnesses in the upper respiratory tract. Disseminated infections also occur, as the kidney disease hemolytic uremic syndrome. Even though vaccination is available, this pathogen is responsible for a worldwide high mortality rate, especially among children from least developed countries, where vaccination strategies are poor or inexistent. It is estimated that 30% of invasive pneumococcal diseases are caused by antibiotic resistant bacteria, leading to the classification of “serious threat” by the World Health Organization. In order to prevent cases of severe illness, investigation in the direction of new vaccine candidates is of upmost importance. Pneumococcal extracellular vesicles pose as ideal candidates for a serotype-independent vaccine formulation. To this purpose, the aspects of vesicle formation, cargo allocation and function need to be understood in detail. Graphical Abstract
cell therapies
2024-10-26 | Gb3 trisaccharide-bearing exosomes as a novel neutralizer for Shiga toxin type 1
Abstract Shiga toxin types 1 (Stx1) and 2 (Stx2), produced by Shiga toxin-producing Escherichia coli (STEC) and Shigella dysenteriae , are key virulence factors responsible for severe foodborne diseases, such as hemorrhagic colitis and hemolytic uremic syndrome (HUS). The receptors for Stxs are Gb3 and P1 glycotope, which contain the Galα1→4Gal epitope and are synthesized by human α1,4-galactosyltransferase (A4galt). Stx-related infections pose a global public health challenge, owing to the limited therapeutic options due to the restricted use of antibiotics. Therefore, there is an urgent need to develop novel therapeutic strategies. This study proposes an innovative strategy utilizing exosomes derived from CHO-Lec2 cells, which were modified with Functional-Spacer-Lipid (FSL) conjugates bearing the Gb3 carbohydrate epitope (exo-Gb3-FSL). Flow cytometry analysis confirmed the presence of Galα1→4Gal disaccharides on exo-Gb3-FSL constructs, enabling them to bind Stx1. Moreover, using CHO-Lec2 cells evaluated the ability of exo-Gb3-FSL agents to bind Stx1 and protect these cells from Stx1-mediated cytotoxicity. For Stx1-treated CHO-Lec2 cells, increased cell survival was observed when using 25 µM exo-Gb3-FSL constructs, compared to control cells. These findings highlight the potential of exosome-based anti-Stx1 agents as promising alternatives to conventional therapies. This innovative strategy may provide novel directions for studies on Stx1 neutralization, offering a valuable strategy for the treatment of Stx-related diseases. Highlights - Exo-Gb3-FSL constructs hold Stx1 binding Galα1→4Gal epitope. - Stx1 was effectively bound by exo-Gb3-FSL constructs. - Exo-Gb3-FSL protected CHO-Lec2 cells from Stx1. - Exo-Gb3-FSL is a promising anti-Stx1 agent.
2023-11-21 | Gb3-Coated Bovine Milk Exosomes as a Practical Neutralizer for Shiga Toxin
Shiga toxin (Stx) is associated with foodborne infections of some Shigella spp. and Shiga toxin-producing Escherichia coli (STEC), leading to life-threatening hemolytic uremic syndrome (HUS). Target-specific therapeutics against HUS are currently unavailable in clinical practice. Herein, we reported the construction and in vitro characterization of Gb3-coated bovine milk exosomes (Gb3-mExo) as a multivalent Shiga toxin neutralizer, utilizing the natural advantages of milk exosomes (mExo) in drug delivery and multivalent interactions between Stx and its receptor Gb3. Gb3-mExo constructs were achieved by conjugating mExo with the Gb3 derivatives containing stearic acid-derived lipid tail, which was prepared through an efficient chemoenzymatic approach. The constructs were able to potently neutralize the binding of the B subunit of Stx2 (Stx2B) to receptor Gb3 immobilized on the plate or expressed on model cells. General safety of the constructs was evidenced by the cytotoxicity analysis and hemolysis assay. In addition to the excellent stability under conventional storage and handling conditions, the construct can also retain most of its neutralization potency under gastrointestinal pH extremes, showing the potential for oral administration. Considering the natural availability and excellent biocompatibility of mExo, Gb3-mExo conjugates should prove to be a practical prophylactic and therapeutic for the Shiga toxin-related infections.
small molecules
2026-09-01 | Gypenosides Mitigate STEC-Induced Intestinal Injury Through Modulation of Ferroptosis Involving the ATF4-CHAC1-GPX4 Axis
Shiga toxin-producing Escherichia coli (STEC) infection causes severe enteropathies and hemolytic uremic syndrome, yet non-antibiotic therapeutic strategies remain limited. This study evaluated whether gypenosides (GPs) protect against STEC-induced intestinal injury and investigated the underlying mechanisms. Mice were pretreated with GPs prior to STEC challenge, and protective effects were comprehensively assessed through survival analysis, bacterial burden quantification, transcriptomic profiling, flow cytometry, electron microscopy, and Western blotting. GPs significantly improved survival rates, alleviated diarrheal symptoms, reduced bacterial dissemination in systemic organs, and lowered Stx2 toxin levels. Furthermore, GPs effectively restored gut microbiota dysbiosis by enriching beneficial bacterial genera. Transcriptomic analysis suggested that GP treatment was associated with suppression of ferroptosis-related signaling pathways. Ultrastructural examination demonstrated ameliorated mitochondrial vacuolization, and biochemical assays confirmed decreased Fe2+ accumulation and attenuated lipid peroxidation. Mechanistically, these changes were associated with modulation of the ATF4-CHAC1-GPX4 axis and suppression of ferroptosis, together with preservation of mitochondrial integrity. Collectively, these findings identify GPs as a promising protective candidate against STEC-induced intestinal injury and highlight the ATF4-CHAC1-GPX4 axis as a candidate pathway for further mechanistic investigation.
2026-08-20 | Beyond Defense: Kidney Mysteries in Inborn Errors of Immunity
Inborn errors of immunity (IEI), formerly termed primary immunodeficiencies, are increasingly recognized as disorders of immune dysregulation rather than infection susceptibility alone. With over 500 validated genes in the 2024 International Union of Immunological Societies (IUIS) classification and approximately one-quarter of patients presenting without infection, autoimmunity, autoinflammation, lymphoproliferation, and malignancy are now core features. The kidney is affected across at least 22 IEI categories, yet renal involvement remains under-recognized. This review proposes a mechanistic framework for IEI-associated kidney disease, encompassing: complement dysregulation (C3 glomerulopathy, atypical hemolytic uremic syndrome from CFH/CFI/C3 variants); immune complex–mediated and monogenic lupus nephritis (C1q, C2, C4, DNASE1L3, and TREX1 defects); autoinflammatory and type I interferonopathy–driven nephropathy; infection-related glomerulonephritis (common variable immunodeficiency [CVID], chronic granulomatous disease); lymphoproliferative and immune-dysregulation syndromes causing interstitial nephritis (ALPS, CTLA-4 and LRBA deficiency); and syndromic IEI with intrinsic structural disease. We outline a stepwise diagnostic approach integrating clinical red flags, complement and immune profiling, kidney biopsy with immunofluorescence and electron microscopy, and genetic testing, emphasizing that genetic diagnosis should precede immunosuppression. The therapeutic landscape is shifting from empirical immunosuppression toward precision medicine, including complement inhibitors (iptacopan, pegcetacoplan, Food and Drug Administration–approved for C3 glomerulopathy in 2025), JAK inhibitors for interferonopathies, leniolisib for activated PI3Kδ syndrome, CTLA4-Ig agents, and curative hematopoietic stem cell transplantation and emerging gene therapy. An illustrative case from Europe’s largest kidney transplant center illustrates a girl with Schimke immuno-osseous dysplasia (SMARCAL1 mutation) presenting with steroid-resistant nephrotic syndrome and focal segmental glomerulosclerosis who underwent kidney transplantation following bone marrow transplant. Recognizing IEI in unexplained nephropathy, combining biopsy with complement and genetic profiling, and early nephrology–immunology collaboration are key to improving renal outcomes and enabling potentially curative therapy.
2026-06-22 | The co-localizing Zorya II, Druantia III, and ARMADA II defense systems on O-island 172 confer synergistic anti-phage defense in enterohemorrhagic Escherichia coli
ABSTRACT In this study, we found that the enterohemorrhagic Escherichia coli (EHEC) strain EDL933 Δ stx1/2 is highly resistant to many phages. The three phage defense systems Zorya II, Druantia III, and DIS ARM -related A ntiviral D efense A rray (ARMADA II) are encoded on O-island 172 (OI-172) in strain EDL933. Sequence comparison revealed that the three phage defense systems co-occur in 426 E. coli strains, including 277 O157:H7 isolates and 117 diverse non-pathogenic strains. Efficiency of plating (EOP) assays was used to explore the phage spectra and synergy of the three defense systems, and their contribution to the phage resistance of the host strain EDL933 Δ stx1/2 . Using Δ zorABE , Δ druHE , and Δ armABCD single system deletion mutants in EDL933 Δ stx1/2 , we showed that Druantia III and ARMADA II significantly protect to different extents against a similar spectrum of phages, including the Drexlerviridae , Queuovirinae , Demerecviridae , Vequintavirinae , Stephanstirmvirinae , and Autographivirales , whereas Zorya II only provided protection against Autographivirales . Further EOP and growth experiments indicated significantly synergistic and additive interactions of Druantia III and ARMADA II against a broad phage spectrum. The defense pair Druantia III and Zorya II was found to interact additively against a few phages. Altogether, our results revealed that Druantia III and ARMADA II are responsible for most of the phage resistance of EDL933 Δ stx1/2 , whereas Zorya II provides additional immunity against Autographivirales . Future studies are underway to elucidate the molecular basis of the synergistic interactions between the Druantia III and ARMADA II defense systems. IMPORTANCE Shiga toxin-producing Escherichia coli strains cause life-threatening diseases, such as hemorrhagic colitis and the hemolytic uremic syndrome. Currently, enterohemorrhagic E. coli (EHEC) infections can only be treated symptomatically, since antibiotics are not recommended due to induction of the Shiga toxin. While phage therapy could offer a treatment option, we found that the EHEC strain EDL933 Δ stx1/2 is highly resistant to many phages. Efficiency of plating (EOP) assays of defense mutants in the host strain revealed that the co-occurring defense systems Zorya II, Druantia III, and DIS ARM -related A ntiviral D efense A rray (ARMADA II) on O-island 172 (OI-172) confer most of the phage resistance in EHEC. Moreover, Druantia III and ARMADA II were shown to interact additively and synergistically in the anti-phage defense in EDL933 Δ stx1/2 , providing a more robust immunity than each system alone. These results support the idea that the discovery of inhibitors or anti-defense proteins against the Druantia III and ARMADA II systems could be combined with phage therapies to efficiently eradicate EHEC.
2025-10-01 | Azithromycin for the Prevention of Hemolytic Uremic Syndrome in Shiga Toxin-Positive Diarrhea: Proof of Concept
Background: During the last decade, it has become increasingly common to diagnose Shiga Toxin-producing Escherichia coli (STEC) infection before hemolytic uremic syndrome (HUS) has developed, providing a potential window of treatment opportunity that, besides generous rehydration, goes underexploited. Antibiotic treatment is historically contraindicated in Shiga Toxin (Stx)-positive diarrhea on the assumption that it may trigger STEC-HUS. However, this concept is based on weak evidence mostly concerning bactericidal agents and it does not apply to bacteriostatic antibiotics. Several in vitro and in vivo studies both on animal models and on human beings indicate that azithromycin may be safe and effective in preventing STEC-HUS or mitigating disease severity. Methods: Within the ItalKid-HUS network, devoted to the screening for Stx of bloody diarrhea in children, we have treated positive patients with azithromycin 10 mg/kg/die orally until the remission of diarrhea (maximum 5 days). The present analysis is meant to be a proof of concept for a future study on the use of azithromycin treatment in STEC infected patients. Results: Forty-seven patients (24 males, median age 6.4 years) with Stx-positive diarrhea were treated with azithromycin. The treatment was started after a median time of 4 days since the onset of symptoms (3 days since the onset of bloody diarrhea) and it was continued for a median time of 5 days. Of the enrolled patients, 8 were positive for Stx1, 18 for Stx2, 8 for both Stx1 and Stx2, and 13 for unspecified Stx. Only one patient out of 47 developed HUS after the first dose of azithromycin, while historical data indicate that the expected number of STEC-HUS was six (conversion in STEC-HUS of 2.1% vs. 15.0%; p < 0.02). No treatment-related side effects have been observed. Conclusion: Azithromycin is safe and may represent a useful therapeutic option in patients with Stx-positive diarrhea to prevent HUS or to mitigate its severity. A controlled study is necessary but, in the meantime, Stx-positive patients should be treated based on the currently available evidence.
2025-08-23 | Bloody diarrhea, STEC infection, and HUS in the molecular microbiology era
Hemolytic uremic syndrome (HUS) associated with Shiga toxin-producing Escherichia coli (STEC) infection remains a major individual and public health challenge throughout the world causing substantial personal, social, and economic burdens. In Western countries, bloody diarrhea (BD) in children is related to STEC infection in at least 6% of cases (rising to 15-20% in summer). This infection may turn into STEC-HUS in about 15% of patients. The widespread use of molecular microbiology leads to the diagnosis of STEC infection before the onset of HUS in an increasing number of patients. The anticipation of the diagnosis creates a window of preventive and/or therapeutic opportunities that include rehydration of dehydrated patients and/or volume expansion that have both proven to mitigate the severity of HUS. Traditionally, antibiotics are not recommended in STEC infections, but recent data suggest a promising potential preventive role for bacteriostatic agents (e.g., azithromycin), if they are given early in the course of the infection. It is recommended to test all children with BD for Shiga toxin (Stx) encoding genes, actively infuse Stx-positive patients with isotonic crystalloid solutions and carefully monitor them with urine dipstick for hemoglobinuria to early identify those who might eventually develop HUS. The suggested approach will increase the detection of STEC-infected patients thus enhancing our knowledge of the mechanisms of disease spreading. The early diagnosis of STEC infection combined with the mentioned therapeutic opportunities will hopefully decrease the number of children suffering from HUS, its case fatality rate and/or improve its short- and long-term outcomes.
antibodies
2026-09-11 | Shiga Toxin-Producing Escherichia coli in Animal Reservoirs, Serotype Diversity, Virulence Profiles, and Antimicrobial Resistance Trends (2020–2026): A Scoping Review
Background/Objectives: Shiga toxin-producing Escherichia coli (STEC) are important zoonotic pathogens associated with gastrointestinal infections and hemolytic–uremic syndrome (HUS). Increasing serotype diversity, emergence of hybrid strains, and growing antimicrobial resistance complicate surveillance and treatment. This review summarizes recent data on STEC isolated from major animal reservoirs between 2020 and 2026. Methods: We comparatively analyzed peer-reviewed, open-access studies investigating STEC from cattle, sheep, goats, poultry, wildlife, and related animal products. We extracted and evaluated data on serotypes, virulence genes, hybrid pathotypes, and antimicrobial resistance determinants. Results: High serotype diversity was observed across all reservoirs, with non-O157 STEC frequently predominating over O157:H7. Ruminant isolates commonly carried stx2 and additional virulence determinants associated with severe human disease, confirming cattle and small ruminants as major reservoirs of highly pathogenic STEC. Poultry-associated isolates showed greater variability in virulence profiles but frequently exhibited high rates of multidrug resistance. Hybrid strains combining virulence traits characteristic of multiple E. coli pathotypes were increasingly reported. Livestock-associated STEC commonly carried resistance determinants against β-lactams, tetracyclines, sulfonamides, quinolones, and polymyxins, whereas wildlife isolates generally showed lower rates of resistance. Conclusions: Animal-associated STEC populations demonstrate increasing genomic diversity, pathogenic potential, and antimicrobial resistance. The growing prevalence of non-O157 and hybrid strains highlights the limitations of traditional serotype-focused surveillance and emphasizes the need for integrated One Health monitoring strategies.
2025-12-01 | ATYPICAL HEMOLYTIC UREMIC SYNDROME: FROM PATHOPHYSIOLOGY TO THERAPEUTIC ADVANCES
Atypical hemolytic uremic syndrome (aHUS) is a rare, life-threatening thrombotic microangiopathy (TMA) distinct from Shiga toxin-producing Escherichia coli (STEC)-related HUS. It is primarily driven by genetic or acquired dysregulation of the complement system, with pathogenic variants in complement factor H (CFH), factor I (CFI), membrane cofactor protein (MCP/CD46), factor B (CFB), and C3 identified in nearly 60% of patients. The resulting uncontrolled activation of the alternative complement pathway leads to endothelial damage, platelet activation, and microvascular thrombosis, most prominently affecting renal function. Clinically, aHUS is characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia, and organ injury, most commonly renal but often involving extra-renal systems such as cardiovascular, neurological, dermatological, and gastrointestinal organs. Diagnosis is challenging, requiring exclusion of other TMAs such as thrombotic thrombocytopenic purpura (TTP) and typical HUS. Early and accurate identification is essential to prevent irreversible organ damage. Diagnostic workup integrates clinical, laboratory, and genetic testing. ADAMTS13 activity measurement is critical to exclude TTP, while Shiga toxin assays help differentiate typical HUS. Complement biomarkers, including soluble C5b-9 and factor Ba, are under investigation for their diagnostic and prognostic utility. Genetic testing, employing next-generation sequencing and MLPA, provides prognostic insights and guides therapy, though penetrance remains incomplete and environmental triggers (infections, pregnancy, transplantation) play a pivotal role. Therapeutically, plasma exchange was historically the first-line option, but outcomes were poor with high rates of end-stage renal disease (ESRD). The advent of complement inhibitors has revolutionized management. Eculizumab, a monoclonal antibody targeting C5, effectively halts terminal complement activation, resulting in rapid hematologic normalization and renal recovery, especially when initiated early. Ravulizumab, a long-acting C5 inhibitor requiring infusions every 8 weeks, offers comparable efficacy with improved quality of life. Real-world studies confirm their sustained safety and effectiveness, though concerns regarding meningococcal infections necessitate vaccination and antibiotic prophylaxis. The duration of therapy remains debated; relapse occurs in 20–30% after discontinuation, particularly in carriers of CFH and CFI mutations. Emerging biomarkers and genetic stratification may enable more personalized discontinuation strategies. Despite therapeutic advances, significant challenges remain. Complement inhibitors impose a lifelong economic burden, raising questions of cost-effectiveness and accessibility. Health-economic analyses highlight the need for balanced strategies between clinical benefit and financial sustainability. Furthermore, gaps persist in standardized diagnostic criteria, access to genetic testing, and long-term outcome data for ravulizumab. Ongoing research focuses on refining biomarkers for risk stratification, identifying novel complement targets, and developing more affordable therapies. Special considerations arise in pregnancy-associated aHUS, post-transplant recurrence, and pediatric populations, where individualized management is critical. In conclusion, aHUS exemplifies a paradigm shift in the treatment of rare complement-mediated diseases. Early recognition, integration of genomic data, and targeted complement inhibition have transformed its prognosis. Future research must focus on optimizing therapeutic duration, expanding access to novel agents, and achieving a cost-effective, precision medicine approach for this devastating disorder.
2025-11-05 | Case Report: Effective use of eculizumab in treating recurrent atypical HUS following renal transplantation triggered by SARS-CoV-2 infection
Atypical hemolytic uremic syndrome (aHUS) is a severe post-transplant complication associated with a high risk of graft loss and mortality. Based on its pathophysiological mechanism, aHUS can be classified into recurrent aHUS (reactivation post-transplantation) and de novo aHUS (new-onset disease after transplantation). This study reports a case of a 52-year-old kidney transplant recipient who developed recurrent aHUS 10 months post-transplantation, triggered by SARS-CoV-2 infection. Genetic analysis revealed mutations in complement-related genes CFHR and C3. Following the diagnosis, the patient received a course of eculizumab induction therapy (900 mg/week for the first 4 weeks), followed by long-term maintenance therapy (900 mg every 2 weeks). Significant clinical improvement was observed, including stabilization of blood pressure, normalization of hemoglobin and lactate dehydrogenase (LDH) levels, an increase in platelet count, and a urine output exceeding 2,000 mL per day. The patient continued regular follow-up after discharge, with stable graft function. This case highlights the potential role of SARS-CoV-2 and other infections as triggers for aHUS recurrence in kidney transplant recipients and further supports the efficacy of eculizumab in treating recurrent aHUS. Furthermore, this study underscores the importance of precise immune risk stratification and early intervention in the effective management of aHUS recurrence.
2025-11-05 | Data Sheet 1_Case Report: Effective use of eculizumab in treating recurrent atypical HUS following renal transplantation triggered by SARS-CoV-2 infection.docx
Atypical hemolytic uremic syndrome (aHUS) is a severe post-transplant complication associated with a high risk of graft loss and mortality. Based on its pathophysiological mechanism, aHUS can be classified into recurrent aHUS (reactivation post-transplantation) and de novo aHUS (new-onset disease after transplantation). This study reports a case of a 52-year-old kidney transplant recipient who developed recurrent aHUS 10 months post-transplantation, triggered by SARS-CoV-2 infection. Genetic analysis revealed mutations in complement-related genes CFHR and C3. Following the diagnosis, the patient received a course of eculizumab induction therapy (900 mg/week for the first 4 weeks), followed by long-term maintenance therapy (900 mg every 2 weeks). Significant clinical improvement was observed, including stabilization of blood pressure, normalization of hemoglobin and lactate dehydrogenase (LDH) levels, an increase in platelet count, and a urine output exceeding 2,000 mL per day. The patient continued regular follow-up after discharge, with stable graft function. This case highlights the potential role of SARS-CoV-2 and other infections as triggers for aHUS recurrence in kidney transplant recipients and further supports the efficacy of eculizumab in treating recurrent aHUS. Furthermore, this study underscores the importance of precise immune risk stratification and early intervention in the effective management of aHUS recurrence.
2025-10-16 | Extracorporeal Membrane Oxygenation and Eculizumab for Cardiac Failure in STEC-HUS
Hemolytic uremic syndrome (HUS) is a complication of Shiga toxin-producing Escherichia coli (STEC) infection that can cause acute renal failure and introduce serious extrarenal organ injury. The most life threatening of these include cardiac failure and thrombocytopenia. Here, we present a case of severe STEC-HUS in a previously healthy 2-year-old boy who progressed to cardiac failure necessitating extracorporeal membrane oxygenation (ECMO). Following ECMO cannulation, he was treated with eculizumab, an anticomplement component 5 monoclonal antibody. The patient required ECMO for 5 days and subsequently survived decannulation with normal cardiac function and a good neurological outcome. This case illustrates the feasibility of ECMO despite the consumptive thrombocytopenia characteristic of HUS as well as the potential role of eculizumab in facilitating cardiac recovery. Additionally, we propose anticoagulation parameters balancing HUS-related thrombocytopenia with hemorrhagic complications while on ECMO. Further studies are warranted to better understand complement dysregulation in the pathophysiology of STEC-HUS and develop treatment guidelines for STEC-HUS with cardiac manifestations.
vaccines
2025-08-13 | In Silico Design of a Multiepitope Vaccine Against Intestinal Pathogenic Escherichia coli Based on the 2011 German O104:H4 Outbreak Strain Using Reverse Vaccinology and an Immunoinformatic Approach
Background: While most Escherichia coli strains are harmless members of the gastrointestinal microbiota, certain pathogenic variants can cause severe intestinal and extraintestinal diseases. A notable outbreak of E. coli O104:H4, involving both enteroaggregative (EAEC) and enterohemorrhagic (EHEC) strains, occurred in Europe, resulting in symptoms ranging from bloody diarrhea to life-threatening colitis and hemolytic uremic syndrome (HUS). Since treatment options remain limited and have changed little over the past 40 years, there is an urgent need for an effective vaccine. Such a vaccine would offer major public health and economic benefits by preventing severe infections and reducing outbreak-related costs. A multiepitope vaccine approach, enabled by advances in immunoinformatics, offers a promising strategy for targeting HUS-causing E. coli (O104:H4 and O157:H7 serotypes) with minimal disruption to normal microbiota. This study aimed to design an immunogenic multiepitope vaccine (MEV) construct using bioinformatics and immunoinformatic tools. Methods and Results: Comparative proteomic analysis identified 672 proteins unique to E. coli O104:H4, excluding proteins shared with the nonpathogenic E. coli K-12-MG1655 strain and those shorter than 100 amino acids. Subcellular localization (P-SORTb) identified 17 extracellular or outer membrane proteins. Four proteins were selected as vaccine candidates based on transmembrane domains (TMHMM), antigenicity (VaxiJen), and conservation among EHEC strains. Epitope prediction revealed ten B-cell, four cytotoxic T-cell, and three helper T-cell epitopes. Four MEVs with different adjuvants were designed and assessed for solubility, stability, and antigenicity. Structural refinement (GALAXY) and docking studies confirmed strong interaction with Toll-Like Receptor 4 (TLR4). In silico immune simulations (C-ImmSim) indicated robust humoral and cellular immune responses. In Conclusions, the proposed MEV construct demonstrated promising immunogenicity and warrants further validation in experimental models.
2023-02-01 | The role of pneumococcal extracellular vesicles on the pathophysiology of the kidney disease Hemolytic Uremic Syndrome
Abstract Streptococcus pneumoniae -induced hemolytic uremic syndrome (Sp-HUS) is a kidney disease characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. This disease is frequently underdiagnosed and its pathophysiology is poorly understood. In this work, we compared clinical strains, isolated from infant Sp-HUS patients, to a reference pathogenic strain D39, for host cytotoxicity and further explored the role of Sp-derived extracellular vesicles (EVs) in the pathogenesis of a HUS infection. In comparison with the WT strain, pneumococcal HUS strains caused significant lysis of human erythrocytes and increased the release of hydrogen peroxide. Isolated Sp-HUS EVs were characterized by performing dynamic light-scattering microscopy and proteomic analysis. Sp-HUS strain released EVs at a constant concentration during growth, yet the size of the EVs varied and several subpopulations emerged at later time points. The cargo of the Sp-HUS EVs included several virulence factors at high abundance, i.e., the ribosomal subunit assembly factor BipA, the Pneumococcal Surface Protein A (PspA), the lytic enzyme LytC, several sugar utilization and fatty acid synthesis proteins. Sp-HUS EVs strongly downregulated the expression of the endothelial surface marker PECAM-1 and were internalized by human endothelial cells. Sp-HUS EVs elicited the release of pro-inflammatory cytokines (IL-1ß, IL-6) and chemokines (CCL2, CCL3, CXCL1) by human monocytes. These findings shed new light on the overall function of Sp-EVs, in the scope of infection-mediated HUS, and suggest new avenues of research for exploring the usefulness of Sp-EVs as therapeutic and diagnostic targets. Importance Streptococcus pneumoniae is a life-threatening human pathogen associated with severe illnesses in the upper respiratory tract. Disseminated infections also occur, as the kidney disease hemolytic uremic syndrome. Even though vaccination is available, this pathogen is responsible for a worldwide high mortality rate, especially among children from least developed countries, where vaccination strategies are poor or inexistent. It is estimated that 30% of invasive pneumococcal diseases are caused by antibiotic resistant bacteria, leading to the classification of “serious threat” by the World Health Organization. In order to prevent cases of severe illness, investigation in the direction of new vaccine candidates is of upmost importance. Pneumococcal extracellular vesicles pose as ideal candidates for a serotype-independent vaccine formulation. To this purpose, the aspects of vesicle formation, cargo allocation and function need to be understood in detail. Graphical Abstract
cell therapies
2024-10-26 | Gb3 trisaccharide-bearing exosomes as a novel neutralizer for Shiga toxin type 1
Abstract Shiga toxin types 1 (Stx1) and 2 (Stx2), produced by Shiga toxin-producing Escherichia coli (STEC) and Shigella dysenteriae , are key virulence factors responsible for severe foodborne diseases, such as hemorrhagic colitis and hemolytic uremic syndrome (HUS). The receptors for Stxs are Gb3 and P1 glycotope, which contain the Galα1→4Gal epitope and are synthesized by human α1,4-galactosyltransferase (A4galt). Stx-related infections pose a global public health challenge, owing to the limited therapeutic options due to the restricted use of antibiotics. Therefore, there is an urgent need to develop novel therapeutic strategies. This study proposes an innovative strategy utilizing exosomes derived from CHO-Lec2 cells, which were modified with Functional-Spacer-Lipid (FSL) conjugates bearing the Gb3 carbohydrate epitope (exo-Gb3-FSL). Flow cytometry analysis confirmed the presence of Galα1→4Gal disaccharides on exo-Gb3-FSL constructs, enabling them to bind Stx1. Moreover, using CHO-Lec2 cells evaluated the ability of exo-Gb3-FSL agents to bind Stx1 and protect these cells from Stx1-mediated cytotoxicity. For Stx1-treated CHO-Lec2 cells, increased cell survival was observed when using 25 µM exo-Gb3-FSL constructs, compared to control cells. These findings highlight the potential of exosome-based anti-Stx1 agents as promising alternatives to conventional therapies. This innovative strategy may provide novel directions for studies on Stx1 neutralization, offering a valuable strategy for the treatment of Stx-related diseases. Highlights - Exo-Gb3-FSL constructs hold Stx1 binding Galα1→4Gal epitope. - Stx1 was effectively bound by exo-Gb3-FSL constructs. - Exo-Gb3-FSL protected CHO-Lec2 cells from Stx1. - Exo-Gb3-FSL is a promising anti-Stx1 agent.
2023-11-21 | Gb3-Coated Bovine Milk Exosomes as a Practical Neutralizer for Shiga Toxin
Shiga toxin (Stx) is associated with foodborne infections of some Shigella spp. and Shiga toxin-producing Escherichia coli (STEC), leading to life-threatening hemolytic uremic syndrome (HUS). Target-specific therapeutics against HUS are currently unavailable in clinical practice. Herein, we reported the construction and in vitro characterization of Gb3-coated bovine milk exosomes (Gb3-mExo) as a multivalent Shiga toxin neutralizer, utilizing the natural advantages of milk exosomes (mExo) in drug delivery and multivalent interactions between Stx and its receptor Gb3. Gb3-mExo constructs were achieved by conjugating mExo with the Gb3 derivatives containing stearic acid-derived lipid tail, which was prepared through an efficient chemoenzymatic approach. The constructs were able to potently neutralize the binding of the B subunit of Stx2 (Stx2B) to receptor Gb3 immobilized on the plate or expressed on model cells. General safety of the constructs was evidenced by the cytotoxicity analysis and hemolysis assay. In addition to the excellent stability under conventional storage and handling conditions, the construct can also retain most of its neutralization potency under gastrointestinal pH extremes, showing the potential for oral administration. Considering the natural availability and excellent biocompatibility of mExo, Gb3-mExo conjugates should prove to be a practical prophylactic and therapeutic for the Shiga toxin-related infections.
small molecules
2026-09-01 | Gypenosides Mitigate STEC-Induced Intestinal Injury Through Modulation of Ferroptosis Involving the ATF4-CHAC1-GPX4 Axis
Shiga toxin-producing Escherichia coli (STEC) infection causes severe enteropathies and hemolytic uremic syndrome, yet non-antibiotic therapeutic strategies remain limited. This study evaluated whether gypenosides (GPs) protect against STEC-induced intestinal injury and investigated the underlying mechanisms. Mice were pretreated with GPs prior to STEC challenge, and protective effects were comprehensively assessed through survival analysis, bacterial burden quantification, transcriptomic profiling, flow cytometry, electron microscopy, and Western blotting. GPs significantly improved survival rates, alleviated diarrheal symptoms, reduced bacterial dissemination in systemic organs, and lowered Stx2 toxin levels. Furthermore, GPs effectively restored gut microbiota dysbiosis by enriching beneficial bacterial genera. Transcriptomic analysis suggested that GP treatment was associated with suppression of ferroptosis-related signaling pathways. Ultrastructural examination demonstrated ameliorated mitochondrial vacuolization, and biochemical assays confirmed decreased Fe2+ accumulation and attenuated lipid peroxidation. Mechanistically, these changes were associated with modulation of the ATF4-CHAC1-GPX4 axis and suppression of ferroptosis, together with preservation of mitochondrial integrity. Collectively, these findings identify GPs as a promising protective candidate against STEC-induced intestinal injury and highlight the ATF4-CHAC1-GPX4 axis as a candidate pathway for further mechanistic investigation.
2026-08-20 | Beyond Defense: Kidney Mysteries in Inborn Errors of Immunity
Inborn errors of immunity (IEI), formerly termed primary immunodeficiencies, are increasingly recognized as disorders of immune dysregulation rather than infection susceptibility alone. With over 500 validated genes in the 2024 International Union of Immunological Societies (IUIS) classification and approximately one-quarter of patients presenting without infection, autoimmunity, autoinflammation, lymphoproliferation, and malignancy are now core features. The kidney is affected across at least 22 IEI categories, yet renal involvement remains under-recognized. This review proposes a mechanistic framework for IEI-associated kidney disease, encompassing: complement dysregulation (C3 glomerulopathy, atypical hemolytic uremic syndrome from CFH/CFI/C3 variants); immune complex–mediated and monogenic lupus nephritis (C1q, C2, C4, DNASE1L3, and TREX1 defects); autoinflammatory and type I interferonopathy–driven nephropathy; infection-related glomerulonephritis (common variable immunodeficiency [CVID], chronic granulomatous disease); lymphoproliferative and immune-dysregulation syndromes causing interstitial nephritis (ALPS, CTLA-4 and LRBA deficiency); and syndromic IEI with intrinsic structural disease. We outline a stepwise diagnostic approach integrating clinical red flags, complement and immune profiling, kidney biopsy with immunofluorescence and electron microscopy, and genetic testing, emphasizing that genetic diagnosis should precede immunosuppression. The therapeutic landscape is shifting from empirical immunosuppression toward precision medicine, including complement inhibitors (iptacopan, pegcetacoplan, Food and Drug Administration–approved for C3 glomerulopathy in 2025), JAK inhibitors for interferonopathies, leniolisib for activated PI3Kδ syndrome, CTLA4-Ig agents, and curative hematopoietic stem cell transplantation and emerging gene therapy. An illustrative case from Europe’s largest kidney transplant center illustrates a girl with Schimke immuno-osseous dysplasia (SMARCAL1 mutation) presenting with steroid-resistant nephrotic syndrome and focal segmental glomerulosclerosis who underwent kidney transplantation following bone marrow transplant. Recognizing IEI in unexplained nephropathy, combining biopsy with complement and genetic profiling, and early nephrology–immunology collaboration are key to improving renal outcomes and enabling potentially curative therapy.
2026-06-22 | The co-localizing Zorya II, Druantia III, and ARMADA II defense systems on O-island 172 confer synergistic anti-phage defense in enterohemorrhagic Escherichia coli
ABSTRACT In this study, we found that the enterohemorrhagic Escherichia coli (EHEC) strain EDL933 Δ stx1/2 is highly resistant to many phages. The three phage defense systems Zorya II, Druantia III, and DIS ARM -related A ntiviral D efense A rray (ARMADA II) are encoded on O-island 172 (OI-172) in strain EDL933. Sequence comparison revealed that the three phage defense systems co-occur in 426 E. coli strains, including 277 O157:H7 isolates and 117 diverse non-pathogenic strains. Efficiency of plating (EOP) assays was used to explore the phage spectra and synergy of the three defense systems, and their contribution to the phage resistance of the host strain EDL933 Δ stx1/2 . Using Δ zorABE , Δ druHE , and Δ armABCD single system deletion mutants in EDL933 Δ stx1/2 , we showed that Druantia III and ARMADA II significantly protect to different extents against a similar spectrum of phages, including the Drexlerviridae , Queuovirinae , Demerecviridae , Vequintavirinae , Stephanstirmvirinae , and Autographivirales , whereas Zorya II only provided protection against Autographivirales . Further EOP and growth experiments indicated significantly synergistic and additive interactions of Druantia III and ARMADA II against a broad phage spectrum. The defense pair Druantia III and Zorya II was found to interact additively against a few phages. Altogether, our results revealed that Druantia III and ARMADA II are responsible for most of the phage resistance of EDL933 Δ stx1/2 , whereas Zorya II provides additional immunity against Autographivirales . Future studies are underway to elucidate the molecular basis of the synergistic interactions between the Druantia III and ARMADA II defense systems. IMPORTANCE Shiga toxin-producing Escherichia coli strains cause life-threatening diseases, such as hemorrhagic colitis and the hemolytic uremic syndrome. Currently, enterohemorrhagic E. coli (EHEC) infections can only be treated symptomatically, since antibiotics are not recommended due to induction of the Shiga toxin. While phage therapy could offer a treatment option, we found that the EHEC strain EDL933 Δ stx1/2 is highly resistant to many phages. Efficiency of plating (EOP) assays of defense mutants in the host strain revealed that the co-occurring defense systems Zorya II, Druantia III, and DIS ARM -related A ntiviral D efense A rray (ARMADA II) on O-island 172 (OI-172) confer most of the phage resistance in EHEC. Moreover, Druantia III and ARMADA II were shown to interact additively and synergistically in the anti-phage defense in EDL933 Δ stx1/2 , providing a more robust immunity than each system alone. These results support the idea that the discovery of inhibitors or anti-defense proteins against the Druantia III and ARMADA II systems could be combined with phage therapies to efficiently eradicate EHEC.
2025-10-01 | Azithromycin for the Prevention of Hemolytic Uremic Syndrome in Shiga Toxin-Positive Diarrhea: Proof of Concept
Background: During the last decade, it has become increasingly common to diagnose Shiga Toxin-producing Escherichia coli (STEC) infection before hemolytic uremic syndrome (HUS) has developed, providing a potential window of treatment opportunity that, besides generous rehydration, goes underexploited. Antibiotic treatment is historically contraindicated in Shiga Toxin (Stx)-positive diarrhea on the assumption that it may trigger STEC-HUS. However, this concept is based on weak evidence mostly concerning bactericidal agents and it does not apply to bacteriostatic antibiotics. Several in vitro and in vivo studies both on animal models and on human beings indicate that azithromycin may be safe and effective in preventing STEC-HUS or mitigating disease severity. Methods: Within the ItalKid-HUS network, devoted to the screening for Stx of bloody diarrhea in children, we have treated positive patients with azithromycin 10 mg/kg/die orally until the remission of diarrhea (maximum 5 days). The present analysis is meant to be a proof of concept for a future study on the use of azithromycin treatment in STEC infected patients. Results: Forty-seven patients (24 males, median age 6.4 years) with Stx-positive diarrhea were treated with azithromycin. The treatment was started after a median time of 4 days since the onset of symptoms (3 days since the onset of bloody diarrhea) and it was continued for a median time of 5 days. Of the enrolled patients, 8 were positive for Stx1, 18 for Stx2, 8 for both Stx1 and Stx2, and 13 for unspecified Stx. Only one patient out of 47 developed HUS after the first dose of azithromycin, while historical data indicate that the expected number of STEC-HUS was six (conversion in STEC-HUS of 2.1% vs. 15.0%; p < 0.02). No treatment-related side effects have been observed. Conclusion: Azithromycin is safe and may represent a useful therapeutic option in patients with Stx-positive diarrhea to prevent HUS or to mitigate its severity. A controlled study is necessary but, in the meantime, Stx-positive patients should be treated based on the currently available evidence.
2025-08-23 | Bloody diarrhea, STEC infection, and HUS in the molecular microbiology era
Hemolytic uremic syndrome (HUS) associated with Shiga toxin-producing Escherichia coli (STEC) infection remains a major individual and public health challenge throughout the world causing substantial personal, social, and economic burdens. In Western countries, bloody diarrhea (BD) in children is related to STEC infection in at least 6% of cases (rising to 15-20% in summer). This infection may turn into STEC-HUS in about 15% of patients. The widespread use of molecular microbiology leads to the diagnosis of STEC infection before the onset of HUS in an increasing number of patients. The anticipation of the diagnosis creates a window of preventive and/or therapeutic opportunities that include rehydration of dehydrated patients and/or volume expansion that have both proven to mitigate the severity of HUS. Traditionally, antibiotics are not recommended in STEC infections, but recent data suggest a promising potential preventive role for bacteriostatic agents (e.g., azithromycin), if they are given early in the course of the infection. It is recommended to test all children with BD for Shiga toxin (Stx) encoding genes, actively infuse Stx-positive patients with isotonic crystalloid solutions and carefully monitor them with urine dipstick for hemoglobinuria to early identify those who might eventually develop HUS. The suggested approach will increase the detection of STEC-infected patients thus enhancing our knowledge of the mechanisms of disease spreading. The early diagnosis of STEC infection combined with the mentioned therapeutic opportunities will hopefully decrease the number of children suffering from HUS, its case fatality rate and/or improve its short- and long-term outcomes.
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Drug Discovery Landscape
3 orphan drug designations for Infection-related hemolytic uremic syndrome, including 1 approved therapy.
3 orphan drug designations for Infection-related hemolytic uremic syndrome, including 1 approved therapy.
Drug | Therapy type | Orphan designation | Clinical trial status | Sponsor |
|---|---|---|---|---|
Bardoxolone methyl | small molecules | EMA | — | [INACTIVE] Alexion Europe |
Chimeric monoclonal antibody to shiga-toxin 1 and 2 | antibodies | EMA | Taro Pharmaceuticals Europe B.V. | |
Epoetin alfa [Epogen] | — | FDA | Approved | Amgen, Inc. |
“Terminated” – programs with discontinued clinical trials, or with no updates reported for 5 years after completion or 12 years after the last trial started.
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