vancomycine

Vancomycin, sometimes written vancomycine in French, is a glycopeptide antibiotic produced by Amycolatopsis orientalis. It is considered an antibiotic of last resort for many severe Gram-positive infections and is used when beta-lactams are ineffective or cannot be used due to allergy. Clinically, vancomycin is available in intravenous form for systemic infections and, in oral form, is reserved for gastrointestinal infections caused by Clostridioides difficile.

Mechanism of action and spectrum

Vancomycin inhibits bacterial cell wall synthesis by binding tightly to the D-alanyl-D-alanine terminus of peptidoglycan precursors. This blocks proper cross-linking and weakens the cell wall. The antibiotic is active mainly against Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), coagulase-negative staphylococci, Streptococcus species, and some Enterococcus species. It exhibits poor activity against most Gram-negative bacteria due to insufficient penetration of the outer membrane. Resistance can occur, most notably in vancomycin-resistant Enterococcus (VRE) strains, which harbor van gene clusters that alter the target site.

Clinical use and pharmacokinetics

Intravenous vancomycin is used for serious systemic infections caused by susceptible Gram-positive organisms, such as bacteremia, endocarditis, osteomyelitis, pneumonia, and complicated skin infections. Oral vancomycin is not absorbed from the gut and is used for treating C. difficile colitis and related conditions. Vancomycin is primarily excreted by the kidneys, and dosing usually requires adjustment in renal impairment. Therapeutic drug monitoring of trough levels is common to optimize efficacy and limit toxicity.

Adverse effects and resistance

Adverse effects include nephrotoxicity, ototoxicity, red man syndrome (a rate-related infusion reaction), and phlebitis at administration sites. The emergence of vancomycin-resistant organisms, particularly VRE, limits use in some settings and underscores the importance of antimicrobial stewardship.