Vancomycin is a bactericidal antibiotic that inhibits cell wall synthesis.
Vancomycin is not appreciably absorbed from a normal gastrointestinal tract after oral administration. Given parenterally, it penetrates into bile and pleural, pericardial, synovial, and ascitic fluids. However, penetration into even inflamed cerebrospinal fluid is low and erratic.
Vancomycin is excreted unchanged by glomerular filtration.
Vancomycin is active against
However, many strains of enterococci and some strains of S. aureus are resistant.
Vancomycin is often used for serious infection and endocarditis caused by the following (except for vancomycin-resistant strains):
Methicillin-resistant S. aureus
Methicillin-resistant coagulase-negative staphylococci
Certain beta-lactam–resistant and multidrug-resistant Streptococcus pneumoniae
Beta-hemolytic streptococci (when beta-lactams cannot be used because of drug allergy or resistance)
Corynebacterium species including C. jeikeium, and C. striatum
Viridans streptococci (when beta-lactams cannot be used because of drug allergy or resistance)
Enterococci (when beta-lactams cannot be used because of drug allergy or resistance)
However, vancomycin is less effective than antistaphylococcal beta-lactams for methicillin-susceptible S. aureus infections. Vancomycin is used with other antibiotics when treating methicillin-resistant coagulase-negative staphylococcal prosthetic valve endocarditis or enterococcal endocarditis. Vancomycin has also been used as an alternative drug for pneumococcal meningitis caused by strains with reduced penicillin sensitivity; however, the erratic penetration of vancomycin into cerebrospinal fluid (especially during concomitant use of dexamethasone) and reports of clinical failures make it less than optimal when used alone to treat pneumococcal meningitis.
Oral vancomycin is used to treat Clostridioides (formerly, Clostridium) difficile–induced diarrhea (pseudomembranous colitis). Vancomycin is recommended over metronidazole for an initial episode of nonsevere C. difficile infection. It is preferred over metronidazole for patients who have severe C. difficile infection and is preferred for patients who do not respond to metronidazole.
Animal reproduction studies with vancomycin have not shown risk to the fetus. Evidence in human studies is inadequate. Vancomycin should be given to pregnant women only if clearly needed. Oral vancomycin can be used to treat C. difficile–induced diarrhea in pregnant women.
Vancomycin enters breast milk, and so its use during breastfeeding is discouraged to prevent disruption of gastrointestinal microflora; however, because oral absorption is poor from a normal gastrointestinal tract, systemic adverse effects in infants are unlikely.
The main concern with vancomycin is
Vancomycin should be infused over ≥ 60 minutes to avoid red-person syndrome (a histamine-mediated reaction that can cause pruritus and flushing on the face, neck, and shoulders). Other hypersensitivity reactions (eg, rash, fever) may occur, especially when therapy lasts for > 2 weeks.
Other adverse effects include reversible neutropenia and thrombocytopenia. Nephrotoxicity is rare unless high doses are used or other nephrotoxins (eg, aminoglycosides) are given concomitantly. Some reports suggest that concomitant use of piperacillin/tazobactam may also increase risk of nephrotoxicity. Phlebitis occurs uncommonly during IV infusion.
Dose-related ototoxicity is unusual with current formulations; incidence is increased when vancomycin is given concurrently with other ototoxic drugs.
Doses used for meningitis must be higher than usual.
Dose reduction is required in renal insufficiency.
In patients with documented or suspected invasive methicillin-resistant S. aureus (MRSA) infection, vancomycin should be dosed to target an area under the concentration-time curve (AUC) of 400 to 600. Targeting troughs as a surrogate marker for achieving an AUC-to-minimum inhibitory concentration (AUC/MIC) ratio of ≥ 400 is no longer recommended. Dose optimization can be done by getting multiple postdistribution levels (1 to 2 hours after the end of the infusion and a trough) and calculating the AUC using first-order kinetic equations, using a software-based Bayesian approach using 1 or 2 levels, or by titrating a continuous infusion to a steady-state concentration of 20 to 25 mcg/mL (13.8 to 17.25 micromol/L). (See also the vancomycin dosing guidelines revised by the American Society of Health-System Pharmacists, the Infectious Diseases Society of America, the Pediatric Infectious Diseases Society, and the Society of Infectious Diseases Pharmacists.)
These dosing recommendations apply only to MRSA and should not be used to guide dosing for other gram-positive infections.
Vancomycin MICs for many pathogens have been increasing during the past decade. Sensitivity for S. aureus based on vancomycin MIC is as follows:
However, infections due to S. aureus with a vancomycin MIC ≥ 2 mcg/mL (≥ 1.4 micromol/L) may respond suboptimally to standard dosing even when the daily AUC is 400 to 600, so the threshold for changing to an alternative therapy should be low for patients with poor clinical response and an MIC of ≥ 2.
Vancomycin dosing guidelines revised by the American Society of Health-System Pharmacists, the Infectious Diseases Society of America, the Pediatric Infectious Diseases Society, and the Society of Infectious Diseases Pharmacists