Vancomycin

[Vancomycin photos]

KEY POINTS

Vancomycin is a glycopeptide antibiotic that inhibits cell wall synthesis in susceptible bacteria by blocking glycopeptide polymerization via binding tightly to the D-alanyl-Dalanine portion of the cell wall precursor
- Presence of the VanA, VanB, VanC or other Van genes can confer vancomycin resistance via a change in the binding site, where D-ala-D-ala becomes D-ala-D-lac
  - Note VRE = vancomycin-resistant Enterococci
- In Staphylococcus aureus thickening of the bacterial cell wall can lead to increased resistance (larger minimum inhibitory concentration [MIC] values) versus vancomycin
  - MRSA with an MIC of 2 to vancomycin has been associated with clinical failure
  - Beware high MICs in MRSA to vancomycin in patients with a history of vancomycin exposure
    - For information on MIC creep, see this
- A common goal for treating Staphylococcus aureus infections is to have an AUC:MIC ratio > 400
Coverage…
- Vancomycin is active against gram positive organisms like Staphylococci, Streptococci and Enterococci
  - Beta-lactams are better than vancomycin for the treatment of methicillin-sensitive Staphylococcus aureus (MSSA)
- Vancomycin is also commonly considered the drug of choice for Corynebacterium
- Oral vancomycin can be used versus Clostridium difficile infection
  - Poor bioavailability means the vanco stays in the gut and will get to the site of infection
  - IV vancomycin given orally is sometimes used for C. difficile diarrhea
  - IV vancomycin given IV should NOT be used for C. difficile diarrhea
- Intrathecal vancomycin can be used for treatment of meningitis
Dosing of IV vancomycin is a major challenge and not simple
- Younger people, burn patients, neuro-trauma and patients in hyper-catabolic states frequently require a large amount of vancomycin to get to therapeutic levels
- People with reduced kidney function generally require less frequent dosing
- People with large actual body weights generally require larger doses
- Patients that are clinically unstable may require daily vancomycin levels and touch-and-go dosing until stable
Vancomycin levels are frequently monitored to balance between efficacy and toxicity
- Vancomycin trough levels above 25 mcg/mL have been associated with nephrotoxicity
  - It is still debated as to whether or not vancomycin can cause nephrotoxicity
- For non-Staph. aureus infections or cellulitis, a common trough goal is 10-15 mcg/mL
- For most infections, particularly Staph. aureus infections, a common trough goal is 15-20 mcg/mL
- A pre-HD level of 15-25 mcg/mL is typically acceptable, as the actual trough occurs during the dialysis session
  - Post-HD levels can be done to, but adequate time after HD must be given to allow for fluid redistribution (usually 2 hours), which means level results frequently come back later in the day, so post-HD levels can be inconvenient
- Patients on continuous renal replacement therapy (CRRT) typically are similar to patients with a creatinine clearance of 20-40 mL/min, but the rate depends on institutional practice
We are still learning how to dose vancomycin, there is really too much to talk about to try to put it all on this webpage. Check out the antimicrobial stewardship program guidelines below and other documents for more in-depth details
Vancomycin can be used for many infection types from bacteremia to infective endocarditis to osteomyelitis to pneumonia to meningitis
Each gram of vancomycin should be infused over at least 60 minutes
- Too rapid of infusion of vancomycin can lead to histamine release which has been referred to as “red man” or “red neck” or “red person” syndrome. However, there has been a call to end use of the term “Red Man Syndrome.
  - THIS IS NOT AN ALLERGY – the infusion can be stopped, the patient given diphenhydramine and then eventually re-start at a slower rate
  - Inappropriate vancomycin allergy labels are a huge deal and should only be applied when true
Beware neutropenia, especially with long-term vancomycin use (weeks)

RESOURCES

Vancomycin

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