Duodenal biopsy of an infant with chronic non-bloody diarrhea shows Enteropathogenic E. coli (EPEC) adhering to enterocytes. The characteristic histopathological finding produced by EPEC is:

• A Villus tip necrosis with crypt abscesses
• B Attaching and effacing lesions with cup-shaped pedestals of actin ✓
• C Microvillus inclusion bodies within enterocytes
• D Apoptotic colonic crypts with pseudomembrane formation

Explanation

EPEC uses a type III secretion system to inject its own receptor Tir into the enterocyte. Intimin, encoded by the eae gene on the LEE pathogenicity island, binds Tir, triggering localized loss of microvilli (effacement) and accumulation of polymerized actin beneath the bacterium, forming the classic attaching and effacing pedestal lesion. Microvillus inclusion disease is a congenital epithelial disorder, and pseudomembranes are caused by C. difficile.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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