Vancomycin is initiated for a patient with Clostridioides difficile colitis. The clinical pharmacist notes this is the wrong route for systemic activity. Which statement correctly explains vancomycin's role in C. difficile infection?
- A Oral vancomycin is not absorbed from the GI tract and acts locally in the colon to reduce the bacterial burden ✓
- B Oral vancomycin is absorbed systemically, achieving high colonic mucosal concentrations
- C IV vancomycin is secreted into bile and achieves therapeutic colonic concentrations
- D Vancomycin treats C. difficile by inhibiting spore germination in the colon
Correct answer: A. Oral vancomycin is not absorbed from the GI tract and acts locally in the colon to reduce the bacterial burden
Explanation
Vancomycin is a large glycopeptide (molecular weight ~1450 Da) that is essentially not absorbed from the intact gastrointestinal tract when given orally. For C. difficile colitis, oral vancomycin acts topically within the colon to suppress the organism without systemic absorption. IV vancomycin does not reach therapeutic colonic concentrations for this infection. Vancomycin inhibits cell wall peptidoglycan synthesis in actively growing bacteria; it does not affect spores.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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