An infant with persistent non-bloody diarrhea has a stool isolate of E. coli that produces neither heat-labile nor heat-stable toxin nor Shiga toxin. Biopsy shows pedestal-forming attachment of bacteria to enterocytes with effacement of microvilli. Which virulence factor mediates the intimate attachment?
- A Intimin encoded by the eae gene ✓
- B Aggregative adherence fimbriae
- C Heat-stable toxin acting on guanylate cyclase
- D Type 1 fimbriae binding mannose receptors
Correct answer: A. Intimin encoded by the eae gene
Explanation
Enteropathogenic E. coli (EPEC) produces the classic attaching and effacing lesion: actin-rich pedestals beneath intimately adherent bacteria with microvillus effacement. Intimin, an outer membrane protein encoded by the eae gene on the locus of enterocyte effacement pathogenicity island, mediates this intimate adhesion via its translocated receptor Tir. Bundle-forming pilus mediates initial localized adherence. The absence of toxin production excludes ETEC and EHEC, and stacked-brick aggregation would indicate EAEC.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.