Infection with E. coli O157:H7 is associated with which serious complication?

• A. Sepsis
• B. Pneumonia
• C. Reactive Arthritis
• D. Hemolytic-Uremic Syndrome

Answer: (D)

Enterohemorrhagic E. coli O157:H7 releases a Shiga-like toxin that injures the lining of small blood vessels, especially in the kidneys. This endothelial damage sets off microangiopathic hemolysis and platelet consumption, producing the classic triad of hemolytic anemia, thrombocytopenia, and acute kidney injury—together known as hemolytic-uremic syndrome. It typically follows a bloody diarrheal illness, particularly in children, and presents with signs of kidney dysfunction (reduced urine output, elevated creatinine) and labs showing schistocytes, high LDH, and low haptoglobin. Management is mainly supportive, with attention to hydration and renal support; antibiotics are generally avoided because they may worsen toxin release. Other potential complications like sepsis, pneumonia, or reactive arthritis are not the hallmark associations of this toxin-producing E. coli, making hemolytic-uremic syndrome the best answer.