A 2-year-old girl develops pallor, decreased urine output, and petechiae 5 days after bloody diarrhea. Hemoglobin is 6.5 g/dL, platelets 30,000/mm3, creatinine 2.4 mg/dL. Peripheral smear shows fragmented red cells. What is the most likely causative organism?

• A Shigella dysenteriae
• B Campylobacter jejuni
• C Salmonella typhi
• D Escherichia coli O157:H7 ✓

Explanation

Typical hemolytic uremic syndrome is the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury following bloody diarrhea in young children. Shiga toxin produced by enterohemorrhagic Escherichia coli O157:H7 injures glomerular endothelium, triggering microthrombi that shear red cells. Antibiotics are avoided because they may increase toxin release. Campylobacter more often precedes Guillain Barre syndrome, Salmonella typhi causes enteric fever, and Shigella dysenteriae can cause HUS but is a far less common cause than STEC in Indian exam convention.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.