A 5-year-old child develops bloody diarrhoea followed by haematuria, anaemia (haematocrit 22%), and platelet count of 45,000/µL on day 7 of illness. Stool culture grows lactose-non-fermenting, sorbitol-negative E. coli O157:H7. The toxin responsible for HUS pathogenesis primarily targets which cell type in the kidney?
- A Podocytes of Bowman's capsule
- B Glomerular endothelial cells (microangiopathic thrombosis) ✓
- C Tubular epithelial cells of the proximal convoluted tubule
- D Juxtaglomerular cells producing renin
Explanation
Haemolytic Uraemic Syndrome (HUS) from E. coli O157:H7 is caused by Shiga toxin 1 and 2 (Stx1, Stx2), which cleave 28S rRNA of the 60S ribosomal subunit, halting protein synthesis. In the kidney, glomerular endothelial cells are the primary target because they express high levels of the Gb3 (globotriaosylceramide) receptor for Stx. Endothelial injury triggers microangiopathic haemolytic anaemia (MAHA), thrombocytopenia, and AKI — the classic triad of HUS. Neutrophils carry Stx to endothelial cells via transcytosis. Antibiotics are CONTRAINDICATED in STEC-associated HUS as they may lyse bacteria and release more Stx. Treatment is supportive with dialysis as needed.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.