Snapshot A 45-year-old man presents to the emergency room for right lower extremity cellulitis. He reports feeling feverish and malaise for the past 2 days and noticed redness and swelling along his right leg. He reports having tripped a few days ago, sustaining a cut on his foot. He denies any recent surgeries or long trips. He has a history of methicillin-resistant Staphylococcus infections. A Doppler is negative for blood clot. On physical exam, he is febrile. He is started on broad-spectrum antibiotics. He requests an anti-histamine prior to infusions, as he has previously had a flushing reaction to this particular antibiotic in the past. (Cellulitis) Introduction Drugs vancomycin Mechanism of action binds to D-Ala-D-Ala, a cell wall precursor, and prevents peptidoglycan formation mainly bactericidal but bacteriostatic against Clostridium difficile Mechanism of resistance not susceptible to beta-lactamases D-Ala-D-Ala mutation to D-Ala-D-Lac, preventing vancomycin from binding Clinical use gram-positive rods and cocci especially methicillin-resistant Staphylococcus aureus (MRSA) ampicillin-resistant Enterococcus Clostridium difficile (oral dose) often reserved for serious infections Adverse effects ROTN Red man syndrome login to view 3 more bullets Ototoxicity Thrombophlebitis Nephrotoxicity login to view 1 more bullet DRESS syndrome Drug Reaction with Eosinophilia and Systemic Symptoms