Glycopeptide Antibiotics
Overview
Glycopeptide antibiotics are a class of antimicrobial agents that inhibit bacterial cell wall synthesis by binding to the D-alanyl-D-alanine terminus of cell wall precursor units.
Vancomycin
Mechanism of Action
- Inhibits cell wall synthesis by binding to D-alanyl-D-alanine
- Prevents transglycosylation and transpeptidation reactions
- Active primarily against Gram-positive bacteria
Spectrum of Activity
Highly Active Against
- Methicillin-resistant Staphylococcus aureus (MRSA)
- Coagulase-negative staphylococci
- Streptococcus species
- Clostridium difficile (oral formulation)
- Enterococcus species (though resistance is emerging)
Resistance Mechanisms
- VanA, VanB, VanC gene clusters in enterococci (VRE)
- Thickened cell wall in staphylococci
- Altered binding sites
Clinical Applications
- MRSA infections (skin and soft tissue, pneumonia, bacteremia)
- Serious staphylococcal infections (penicillin-allergic patients)
- C. difficile colitis (oral vancomycin)
- Prophylaxis in certain surgical procedures
Adverse Effects
Common
- Red man syndrome (histamine release, infusion-related)
- Nephrotoxicity (especially with aminoglycosides)
- Ototoxicity (rare, usually with high levels)
Monitoring Required
- Serum trough levels (15-20 μg/mL for serious infections)
- Renal function monitoring
- Complete blood counts (bone marrow suppression rare)
Administration
- Intravenous for systemic infections
- Oral for C. difficile colitis (minimal systemic absorption)
- Slow infusion over 1-2 hours to prevent red man syndrome