Shiga Toxin-Associated Hemolytic Uremic Syndrome

1. Disease Information

STEC-HUS is a thrombotic microangiopathy (TMA) defined by the classic triad of microangiopathic hemolytic anemia (Coombs-negative, with schistocytes), thrombocytopenia, and acute kidney injury, arising typically 5–10 days after an episode of (often bloody) diarrhea caused by STEC. It is the prototypical "typical" / diarrhea-associated (D+) HUS and is the leading cause of acute kidney injury in young children.

Identifiers / synonyms: MONDO:0019536. Synonyms: STEC-HUS; typical HUS; diarrhea-positive (D+) HUS; diarrhea-associated HUS; "classic" HUS; (historically) post-diarrheal HUS. ICD-10 D59.3 (hemolytic-uremic syndrome); MeSH D006463 (Hemolytic-Uremic Syndrome). No OMIM entry (acquired disease).

Information source: derived chiefly from aggregated disease-level resources — surveillance networks (US CDC FoodNet), national pediatric registries (Polish, Italian, French), and clinical cohorts — rather than single-patient EHR data.

2. Etiology

Primary cause (infectious): ingestion of STEC producing Shiga toxin(s). Transmission is fecal-oral via contaminated undercooked ground beef, unpasteurized milk/juice, contaminated produce (leafy greens, sprouts), petting-zoo/farm-animal contact, recreational/drinking water, and person-to-person spread. Cattle are the principal reservoir (asymptomatic carriage). Infectious dose is very low (~10–100 organisms).

Required virulence determinant: the Shiga toxins (Stx1 and/or Stx2). Stx2 — particularly subtypes Stx2a — is strongly associated with progression to HUS, whereas Stx1-only strains more often cause uncomplicated diarrhea. Additional STEC virulence factors: the LEE pathogenicity island encoding intimin (eae) and the type III secretion system that mediates attaching-and-effacing (A/E) lesions on gut epithelium.

Risk factors: - Host-demographic: age < 5 years (highest risk), extremes of age, bloody diarrhea, elevated WBC, fever. - Iatrogenic: antibiotic exposure during STEC colitis (especially bactericidal/fluoroquinolone/β-lactam agents may induce the SOS response and increase phage-mediated Stx release) and antimotility agents — both associated with increased HUS risk. - Microbial: Stx2-producing strains, O157:H7, strains carrying stx2a + eae. - Genetic modifiers (not causal): rare variants in complement regulatory genes (CFH, CD46/MCP, CFI, C3) are reported in a subset with severe/atypical course and may worsen outcome; Gb3 synthase (A4GALT) expression levels on host endothelium modulate susceptibility.

Protective factors: adequate cooking of meat, pasteurization, hand hygiene, safe water; these are environmental/public-health, not molecular. No well-established protective genetic allele. Avoiding antibiotics and antimotility agents during suspected STEC colitis is protective against HUS progression.

Gene–environment interaction: the pathogenic outcome is set by the STEC stx2 genotype (environmental/microbial) interacting with host Gb3 tissue distribution and complement regulatory reserve — the same toxin dose produces disparate outcomes depending on host endothelial Gb3 density and complement-regulation capacity.

3. Phenotypes (with suggested HPO terms)

Prodrome / GI (preceding): - Diarrhea, frequently bloody (hemorrhagic colitis) — HP:0002014 (Diarrhea), HP:0025085 (Bloody diarrhea); abdominal pain HP:0002027; vomiting HP:0002013.

Core triad: - Microangiopathic hemolytic anemia — HP:0001937 (Microangiopathic hemolytic anemia); schistocytes on smear; HP:0001878 (Hemolytic anemia). - Thrombocytopenia — HP:0001873. - Acute kidney injury — HP:0001919; oliguria/anuria HP:0100519; often requiring dialysis.

Renal / laboratory: - Hematuria HP:0000790, proteinuria HP:0000093, elevated creatinine HP:0003259; hypertension HP:0000822; elevated LDH, low haptoglobin, negative direct Coombs.

Extrarenal (severity markers): - CNS involvement (~20–25% of severe cases): seizures HP:0001250, encephalopathy HP:0001298, stroke HP:0001297, altered consciousness HP:0030213 — a major determinant of acute mortality. - Pancreatic: hyperglycemia/pancreatitis HP:0001954, HP:0012090. - Cardiac (rare): HP:0001635; colonic complications: intussusception, necrosis, perforation.

Phenotype characteristics: acute onset, predominantly pediatric (<5 yr); severe but usually self-limited acute phase; monophasic course (vs relapsing aHUS). HUS develops in roughly 5–15% of STEC O157 infections, higher in young children. Quality-of-life impact is driven by the minority with CKD/hypertension/proteinuria sequelae at long-term follow-up.

4. Genetic / Molecular Information

No human causal gene. The operative genetics are bacterial: stx1, stx2 (and subtypes stx2a–stx2g) carried on lambdoid prophages; eae (intimin), ehxA (enterohemolysin), LEE locus.

Host molecular determinants: - A4GALT — encodes Gb3/CD77 synthase; Gb3 is the obligate Stx receptor. Tissue-specific Gb3 expression (high on human renal glomerular endothelium and podocytes, cerebral endothelium) explains organ tropism. - Complement modifier genes (CFH, CD46, CFI, C3, CFB) — rare variants reported in severe STEC-HUS; modifiers of severity, not disease cause.

No ACMG-classified pathogenic germline variants define the disease; it is not inherited, has no Mendelian inheritance pattern, no penetrance/expressivity/anticipation, and no founder effect. Allele-frequency/somatic-vs-germline sections are not applicable. Epigenetic/chromosomal abnormalities: not applicable.

5. Environmental Information

• Infectious agent: Escherichia coli (STEC/EHEC) — NCBITaxon:562 (E. coli); O157:H7 lineage. Shiga toxin as the effector (CHEBI/ontology: Shiga toxin is a protein, not a small molecule).
• Vehicles/exposures: undercooked beef, unpasteurized dairy, contaminated produce and water, animal/farm contact; large foodborne outbreaks (e.g., the 2011 German O104:H4 sprout outbreak).
• Lifestyle/iatrogenic: antibiotic and antimotility use during STEC colitis (risk-increasing).

6. Mechanism / Pathophysiology

Ordered causal chain

1. Ingestion of STEC → colonization of the colon; intimin-mediated attaching-and-effacing lesions on colonic epithelium → hemorrhagic colitis (bloody diarrhea).
2. Local Shiga toxin production by phage-borne stx genes → toxin translocates across the gut epithelium into the circulation (transcellular/paracellular; leukocyte- and possibly extracellular-vesicle–associated carriage). Mechanism of systemic delivery partly inferred.
3. Toxin (AB₅ holotoxin) binds Gb3/CD77 on the surface of Gb3-rich target cells — chiefly human renal glomerular microvascular endothelium and podocytes, and cerebral endothelium. (Receptor = globotriaosylceramide; GO: receptor binding.)
4. Retrograde intracellular transport: endocytosis → Golgi → endoplasmic reticulum; the A-subunit is cleaved (furin) and reduced, releasing the A1 fragment into the cytosol.
5. A1 fragment acts as an RNA N-glycosidase → depurinates a single adenine in the 28S rRNA of the 60S ribosomal subunit → halts protein synthesis → cell injury. (This is the canonical demonstrated enzymatic lesion.)
6. Branch A — ribotoxic stress response: ribosomal damage activates p38 and JNK MAPK signaling → apoptosis and pro-inflammatory cytokine/chemokine induction (IL-8, IL-6, TNF). (Demonstrated in intestinal epithelial and endothelial cells.)
7. Branch B — endothelial activation (sublethal toxin): at sublethal doses Stx reprograms endothelial gene expression rather than killing → NF-κB activation → upregulated adhesion molecules, chemokines, tissue factor, and P-selectin → loss of thromboresistance → prothrombogenic endothelium.
8. Complement amplification: Stx2 binds complement factor H, impairing regulation, and induces P-selectin, which activates C3 via the alternative pathway on the endothelial surface → local complement deposition amplifies injury and platelet-thrombus formation. (Mechanistic link established in vitro; drives the eculizumab rationale.)
9. von Willebrand factor axis: Stx promotes endothelial secretion of ultra-large VWF multimers and impairs their ADAMTS13 cleavage → platelet capture → microvascular platelet-fibrin thrombi.
10. Microvascular thrombosis + mechanical RBC shearing across occluded/fibrin-laden capillaries → schistocytes, intravascular hemolysis (↑LDH, ↓haptoglobin) and platelet consumption (thrombocytopenia).
11. Glomerular TMA → endothelial swelling, capillary occlusion, podocyte injury → acute kidney injury (oliguria/anuria). Extrarenal Gb3-rich beds (brain, pancreas) → CNS and pancreatic complications.

Supporting detail

• Molecular pathways: NF-κB; p38/JNK MAPK (ribotoxic stress); alternative complement pathway; VWF–ADAMTS13; coagulation (tissue factor).
• Cellular processes: inhibition of translation; apoptosis (GO:0006915); inflammation; endothelial activation; platelet aggregation; thrombosis (GO:0007596 — blood coagulation).
• Protein dysfunction: Stx A-subunit RNA N-glycosidase activity (enzymatic, not host-protein misfolding).
• Cell types (CL): glomerular endothelial cell (CL:1001005 / CL:0002262 endothelial cell of vascular tree), podocyte (CL:0000653), platelet (CL:0000233), colonic epithelial cell (CL:0011108), monocyte/macrophage (CL:0000235).
• Immune involvement: innate inflammatory cytokine storm; complement activation; neutrophil-mediated endothelial injury (Stx bound to neutrophils).
• Tissue damage mechanisms: ischemia from microvascular occlusion, apoptosis, oxidative/inflammatory injury, fibrin deposition.

7. Anatomical Structures Affected (UBERON)

• Primary organ: kidney — UBERON:0002113; specifically the renal glomerulus (UBERON:0000074) and its microvascular endothelium; podocytes. Renal cortex.
• GI tract (initiating site): colon — UBERON:0001155 (hemorrhagic colitis).
• Secondary/extrarenal: brain UBERON:0000955 (cerebral microvasculature — CNS TMA), pancreas UBERON:0001264, occasionally heart UBERON:0000948.
• Body systems: urinary/renal, hematologic/vascular, gastrointestinal, nervous.
• Tissue/cell level: vascular endothelium (microvascular), glomerular visceral epithelium (podocytes); subcellular — Stx trafficks through endosome → Golgi (GO:0005794) → ER (GO:0005783) → cytosol/ribosome (GO:0005840).
• Localization: bilateral renal involvement.

8. Temporal Development

• Onset: acute, predominantly pediatric; HUS emerges ~5–13 days after onset of diarrhea (median ~1 week), often as diarrhea begins to resolve.
• Progression: acute phase over days to a few weeks; monophasic/self-limited in most. Oligoanuric AKI may require dialysis for days–weeks.
• Course pattern: typically non-relapsing (unlike aHUS). Critical intervention window = early supportive/volume management during the colitis prodrome, before full TMA.
• Duration/remission: most children recover kidney function within weeks (treatment-/supportive-care-associated), but a minority progress to chronic kidney disease; long-term renal sequelae (hypertension, proteinuria, reduced GFR) reported in ~25–30% at ≥5-year follow-up.

9. Inheritance and Population Epidemiology

• Inheritance: none — acquired infectious disease (no AD/AR/X-linked pattern; penetrance/expressivity/consanguinity/carrier-frequency sections not applicable).
• Epidemiology (children):
• Pediatric STEC-HUS incidence varies by country/surveillance: e.g. ~0.5 per 100,000 children/year; Polish registry mean ~3.9 per million age-related population (rising over 2012–2023); French data: >4 cases/100,000 in children <3 yr.
• ~5–15% of STEC O157 infections progress to HUS; FoodNet reported ~6.3% of O157 infections and 15.3% of HUS among children <5 yr.
• Mortality / outcome: low in modern cohorts — ~2–4% case fatality (Polish registry 2% for STEC-HUS; Italian network 3.4% STEC-HUS vs 8.3% aHUS; US FoodNet ~3% in <5 yr with HUS). Older surveillance: 3–5% death, 10–30% long-term renal dysfunction.
• Demographics: highest in young children (1–2 yr highest for non-O157 O26/O80; O157 across childhood); summer/warm-season peak; geographic variation in serogroups (O157 historically dominant in North America/UK; O80/O26 rising in Europe; O104:H4 in the 2011 German outbreak affected mostly adults).
• Sex: roughly equal, slight female predominance reported in some series.

10. Diagnostics

• Clinical/laboratory triad: microangiopathic hemolytic anemia (schistocytes, ↑LDH, ↓haptoglobin, negative direct Coombs), thrombocytopenia, and acute kidney injury (↑creatinine). Supportive: hematuria, proteinuria.
• Microbiologic confirmation of STEC: stool testing — PCR for stx1/stx2 genes (most sensitive; combined with culture raises detection to ~70%), Shiga toxin immunoassay (EIA), and stool culture on sorbitol-MacConkey agar (O157 is sorbitol-nonfermenting; misses non-O157 and sorbitol-fermenting O157). Send stool/rectal swab early — absence of STEC in stool does not exclude STEC-HUS (toxin may clear by the time HUS presents). Serology (anti-O157 LPS antibodies) aids diagnosis when stool is negative.
• Imaging / other: renal ultrasound (nonspecific); neuroimaging (MRI) if CNS involvement.
• Essential differential diagnosis: aHUS/complement-mediated HUS (no diarrhea prodrome, relapsing, complement variants) and TTP (severe ADAMTS13 <10% activity). Distinguishing STEC-HUS from aHUS/TTP is critical because management differs (STEC-HUS = supportive; aHUS = eculizumab; TTP = plasma exchange). LOINC-codable: stool Shiga toxin EIA, stx PCR, ADAMTS13 activity, schistocyte count, LDH, haptoglobin, platelet count, creatinine.
• Genetic/omics testing: complement gene panel only when aHUS is suspected (negative STEC workup, atypical/relapsing course).
• Screening: public-health STEC surveillance and outbreak investigation; no individual genetic screening applicable.

11. Outcome / Prognosis

• Survival: acute case fatality ~2–4% (modern pediatric cohorts); death driven mainly by severe CNS involvement or multi-organ failure.
• Recovery: majority of children recover kidney function; acute dialysis common but usually temporary.
• Long-term morbidity: ~25–30% of survivors have renal sequelae at ≥5 yr (hypertension, proteinuria, reduced GFR, CKD); a small fraction progress to ESKD.
• Prognostic factors (poor): early anuria / prolonged dialysis, high peak WBC, CNS involvement, Stx2 (vs Stx1) genotype, young age, need for dialysis >2–3 weeks. These predict chronic kidney outcomes.

12. Treatment (with suggested NCIT terms)

Mainstay = supportive care; there is no approved antitoxin. - Supportive care (NCIT:C15747 Supportive Care): careful IV volume expansion/early isotonic fluids (NCIT:C15317 Fluid Therapy — early hydration during colitis may be renoprotective), electrolyte and acid-base management, blood pressure control, transfusion of packed RBCs for anemia (NCIT:C15280 Blood Transfusion; platelet transfusion generally avoided unless bleeding/procedure). - Renal replacement therapy (NCIT:C15431? — Dialysis, NCIT:C15248): hemodialysis/peritoneal dialysis/CKRT for oligoanuric AKI. - AVOID: antibiotics (NCIT:C254 Antibiotic) in confirmed/suspected STEC — no proven benefit, possible increased HUS risk (especially bactericidal agents); antimotility agents; NSAIDs. - Plasma exchange (NCIT:C50111 Plasmapheresis/Therapeutic Plasma Exchange): not routinely beneficial in children (reserved, controversially, for severe neurologic disease or adults in outbreak settings). - Eculizumab (NCIT:C64762 Eculizumab; complement C5 inhibitor; monoclonal antibody, NCIT:C20401): controversial and not standard. A randomized placebo-controlled trial (100 children) showed no benefit on acute dialysis need, hematologic course, or extrarenal manifestations; systematic review found no definite medium/long-term benefit. Some centers reserve it empirically for severe CNS involvement, acknowledging weak evidence. - Experimental / investigational: Stx-neutralizing agents, Shiga toxin receptor analogs/binders, anti-Stx monoclonal antibodies, and complement-pathway agents — remain investigational (ClinicalTrials.gov). - Pharmacogenomics: not applicable.

13. Prevention

• Primary prevention (public health, dominant): thorough cooking of ground beef, pasteurization of milk/juice, produce and water safety, hand hygiene, exclusion of cases from food handling/childcare, careful farm/petting-zoo hygiene. Vector/reservoir control (cattle). NCIT:C15417? Health Education / Hygiene.
• Secondary prevention: early recognition of STEC colitis and early IV hydration, and avoidance of antibiotics/antimotility agents to reduce HUS progression; close hematologic/renal monitoring of children with bloody diarrhea.
• Tertiary prevention: BP control and nephroprotection (ACE inhibition) and long-term renal surveillance in survivors to limit CKD progression.
• Immunization: no licensed human vaccine; STEC/Stx and cattle vaccines are investigational.
• Counseling/genetic screening: not applicable (non-genetic).

14. Other Species / Natural Disease

• Reservoir: cattle (Bos taurus, NCBITaxon:9913) and other ruminants carry STEC asymptomatically in the gut — the principal zoonotic source. Deer, sheep, goats also carry STEC.
• Natural disease / comparative biology: classic HUS-like renal TMA is largely human-specific because Gb3 distribution differs by species — human glomerular endothelium is Gb3-rich, whereas mice express Gb3 mostly extraglomerularly, so animals rarely develop the full human renal phenotype naturally.
• Zoonotic potential: high — STEC is a foodborne/zoonotic pathogen; animals are carriers rather than HUS patients.

15. Model Organisms

• Mouse models (NCBITaxon:10090): purified Stx injection, STEC gavage, and streptomycin-treated oral infection models; reproduce systemic toxicity, renal injury and neurologic signs but incompletely recapitulate human glomerular TMA due to different Gb3 tissue distribution. Widely used for toxin trafficking, complement, and therapeutic testing.
• Rabbit, baboon/non-human primate, piglet (gnotobiotic/neonatal) models reproduce aspects of gut colonization, systemic Stx effects, and CNS/renal injury (piglet neurologic model notable).
• In vitro: human glomerular microvascular endothelial cells, podocytes, HUVEC, intestinal epithelial (Caco-2/HCT-8), THP-1 macrophages, and kidney organoids — the most faithful systems for the human Gb3-dependent endothelial/podocyte mechanism.
• Limitations: species Gb3 differences; most models require supraphysiologic toxin doses; natural monophasic human course hard to model.
• Resources: MGI; ATCC/Cellosaurus (cell lines); published organoid protocols.

Key Citations (verify PMIDs with just fetch-reference before KB use)

• MDPI Toxins (2020) — "Shiga Toxin-Associated Hemolytic Uremic Syndrome: A Narrative Review" — mdpi.com/2072-6651/12/2/67 (comprehensive mechanism/clinical review).
• "Shiga toxin-associated hemolytic uremic syndrome: pathophysiology of endothelial dysfunction" — PubMed 20424866.
• Shiga Toxin Classification, Structure, and Function (ASM, EHEC-0024-2013) — PMC4270005 (A-subunit RNA N-glycosidase, retrograde transport).
• Ribotoxic stress response (p38/JNK, apoptosis), Infect Immun 2003 — journals.asm.org/doi/10.1128/iai.71.3.1497-1504.2003.
• Stx–VWF–ADAMTS13, Blood 2005 — ashpublications.org/blood/article/106/13/4199.
• Shiga toxin targets the podocyte via endothelial complement activation — PMC7617617 (PMID not confirmed — browser block; verify before citing).
• New insights into Stx-mediated endothelial dysfunction, Virulence 2013 — tandfonline.com/doi/full/10.4161/viru.26143.
• HUS and death in E. coli O157:H7 infection, FoodNet 2000–2006, CID 2009 — PubMed 19827953.
• Incidence, risk factors, outcome in children — PMC7385025.
• Polish Pediatric HUS Registry prospective cohort (2024) — PMC11546500.
• Sporadic pediatric STEC-HUS, France 2012–2021, Emerg Infect Dis 2023 — wwwnc.cdc.gov/eid/article/29/10/23-0382_article.
• Eculizumab / supportive-care management review (2025) — Frontiers Pharmacol 2025.1535407.
• UK Kidney Association — HUS clinician information — ukkidney.org/rare-renal.

Evidence-type note for KB population: mechanistic claims (steps 3–9) are predominantly IN_VITRO/MODEL_ORGANISM; epidemiology and outcome claims are HUMAN_CLINICAL (registry/surveillance); eculizumab-ineffectiveness is HUMAN_CLINICAL (RCT). A dismech entry for this disease already exists (kb/disorders/Shiga_Toxin-Associated_Hemolytic_Uremic_Syndrome.yaml); reconcile against it and verify every PMID/exact snippet with just fetch-reference and just count-verified-snippets before curating.

Sources: - MDPI Toxins narrative review - Endothelial dysfunction pathophysiology (PubMed 20424866) - Shiga Toxin structure/function PMC4270005 - Ribotoxic stress response, Infect Immun 2003 - Stx/VWF/ADAMTS13, Blood 2005 - Podocyte/complement PMC7617617 - Virulence 2013 endothelial dysfunction - FoodNet HUS/death CID (PubMed 19827953) - Incidence/risk/outcome children PMC7385025 - Polish Pediatric HUS Registry PMC11546500 - France 2012–2021 EID 2023 - Frontiers Pharmacology 2025 management - UK Kidney Association HUS - EHEC diagnosis/management overview

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Term Validation

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Terms the report names something else

These identifiers resolve, so nothing about them looks wrong, and the ontology calls them something unrelated to what the report calls them. That usually means the identifier is not the one the sentence needs:

• HP:0030213 (1 mention) - the report calls it "a major determinant of acute mortality"; HP calls it Emotional dearth
• UBERON:0001155 (1 mention) - the report calls it "hemorrhagic colitis"; UBERON calls it colon
• UBERON:0000955 (1 mention) - the report calls it "cerebral microvasculature — CNS TMA"; UBERON calls it brain

Terms whose name is worth a second look

The report's name for these is recognisably related to the term's own name without being one of them. A loose paraphrase reads the same way as a citation of the wrong sibling term - and so does a related synonym, which the ontology records precisely because it names something adjacent rather than the same thing - so these are listed rather than judged:

• NCBITaxon:10090 (1 mention) - the report calls it "Mouse models"; NCBITaxon calls it Mus musculus, and lists "house mouse" among its other names