A young woman with recurrent acute pyelonephritis has E. coli isolated from midstream urine. Adhesion studies show that the strain binds specifically to globoside (P blood group antigen) on uroepithelial cells. Which adhesin accounts for this tropism?
- A Type 1 fimbriae
- B P fimbriae (Gal-Gal pili) ✓
- C Dr fimbriae recognizing decay-accelerating factor
- D Bundle-forming pilus
Correct answer: B. P fimbriae (Gal-Gal pili)
Explanation
Uropathogenic E. coli strains causing pyelonephritis carry P fimbriae (pyelonephritis-associated pili), which recognize the Gal-alpha1-4-Gal disaccharide of the P blood group antigen globoside on renal epithelial cells. This receptor specificity explains why individuals expressing higher levels of P antigen are more susceptible to pyelonephritis. Type 1 fimbriae bind mannose residues and contribute mainly to cystitis and bladder colonization, not upper tract tropism.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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