From the publishers of The New England Journal of Medicine

Save time and stay informed. Our physician-editors offer you clinical perspectives on key research and news.

  1. Home>
  2. Specialties>
  3. Infectious Diseases>
  4. Summary and Comment

Vancomycin for Staph Infections: Bactericidal Effect Essential

With MRSA infections, vancomycin treatment can fail even when diagnostic lab reports indicate susceptibility.

Although vancomycin remains the standard of care for treating serious methicillin-resistant Staphylococcus aureus (MRSA) infections, several studies have suggested that overall, it is less clinically effective than ß-lactam antibiotics (see Journal Watch Infectious Diseases Jul 28 2003). Now, to better define the limitations of vancomycin therapy, investigators have tested in vitro bactericidal activity of vancomycin (16 µg/mL) in 30 strains of MRSA that are considered to be susceptible to this agent. The isolates, collected from 1998 through 2001, came from patients enrolled -- generally because of vancomycin treatment failure -- in multicenter prospective trials of alternative antibiotic therapy for MRSA bacteremia.

The strains varied widely in susceptibility, with 72-hour killing that ranged from 0.17 to 8.16 log10 colony-forming units per milliliter. Mean killing was 6.26 log10 CFU/mL for the 7 strains associated with vancomycin treatment success and 4.88 log10 CFU/mL for the 23 strains associated with treatment failure (P=0.07). Clinical efficacy was 55.6% for strains with MICs ≤0.5 µg/mL but only 9.5% for strains with MICs of 1 or 2 µg/mL (P=0.01).

Comment: This study is very small, but the results provide objective support for the clinical observations on limitations of vancomycin for serious MRSA infections, particularly for strains with relatively high MICs. Unfortunately, the in vitro bactericidal assay used in this study cannot be readily replicated in clinical laboratories. Additionally, as noted by the authors, most isolates came from patients with vancomycin treatment failure, so extrapolating from these results to the interpretation of standard laboratory MIC determinations is inappropriate.

— Richard T. Ellison III, MD

Published in Journal Watch Infectious Diseases July 9, 2004

Citation(s):

Sakoulas G et al. Relationship of MIC and bactericidal activity to efficacy of vancomycin for treatment of methicillin-resistant Staphylococcus aureus bacteremia. J Clin Microbiol 2004 Jun; 42:2398-402.

Your Remark:

Reader Remarks are intended to encourage lively discussion of clinical topics with your peers in the medical community. Please consider this when composing your remark.

Fields marked with an * are required.

Name as you'd like it to appear:

Submitting a comment indicates you have read and agreed to the remark guidelines and declare:*

PRIVACY: We will not use your email address, submitted for a comment, for any other purpose nor sell, rent, or share your e-mail address with any third parties. Please see our Privacy Policy.

 

CLEAR erases anything you've added in any part of the form. CONTINUE allows you to check your entire post (and edit it if necessary) before submitting.

To ensure that your Reader Remark is not formatted as one long paragraph, precede new paragraphs with either a blank line or an indentation.

Search

Advanced

Article Tools

Reader Remarks

Sign-In

Forgot your password?

New to Journal Watch?

E-mail Alerts

Delivered to your inbox.
Tailored to your interests. Free.

Sign Up Now!

Journal Watch Newsletters

Available in 13 specialties with convenient delivery and 10 free online CME exams.

Subscribe Now!

Copyright © 2004. Massachusetts Medical Society. All rights reserved.