Vancomycin

Exam items hinge on route matching the infection: IV vancomycin treats systemic MRSA but does not treat C. difficile because it doesn’t reach the colon, while oral vancomycin treats C. diff precisely because it stays in the gut and is largely not absorbed into the bloodstream (serum levels stay low — though an inflamed bowel plus renal impairment can cause systemic accumulation). The classic trap is the patient who develops flushing, pruritus, and hypotension during an infusion — the answer is to slow or briefly hold the infusion and give an antihistamine, not to discontinue and mislabel it a penicillin-style allergy. This is a rate-related histamine (anaphylactoid) reaction, not a true IgE allergy; true anaphylaxis (wheezing, angioedema) is the discontinue answer.

For monitoring, current practice favors AUC/MIC-guided dosing (target ~400–600) over trough-only. Rising creatinine or BUN signals nephrotoxicity; new tinnitus or hearing loss signals ototoxicity. Don’t confuse this with ciprofloxacin’s tendon-rupture warning — different antibiotic, different harm. Hook: “Red man = slow the can.”