Vancomycin

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
    - pretreat with antihistamines and slow infusion rate
    - vancomycin directly causes degranulation of mast cells and histamine release
    - characterized by a pruritic, erythematous rash of the face, neck, and upper trunk within minutes to days of vancomycin exposure
  - Ototoxicity
  - Thrombophlebitis
  - Nephrotoxicity
    - must be renally dosed in patients with renal impairment
- DRESS syndrome
  - Drug Reaction with Eosinophilia and Systemic Symptoms