Effect of vancomycin minimal inhibitory concentration on the outcome of methicillin-susceptible Staphylococcus aureus endocarditis.

Abstract

BACKGROUND:

Staphylococcus aureus endocarditis has a high mortality rate. Vancomycin minimum inhibitory concentration (MIC) has been shown to affect the outcome of methicillin-resistant S. aureus bacteremia, and recent data point to a similar effect on methicillin-susceptible S. aureus bacteremia. We aimed to evaluate the effect of vancomycin MIC on left-sided S. aureus infective endocarditis (IE) treated with cloxacillin.

METHODS:

We analyzed a prospectively collected cohort of patients with IE in a single tertiary-care hospital. Vancomycin, daptomycin, and cloxacillin MIC was determined by E-test. S. aureus strains were categorized as low vancomycin MIC (<1.5 µg/mL) and high vancomycin MIC (≥1.5 µg/mL). The primary endpoint was in-hospital mortality.

RESULTS:

We analyzed 93 patients with left-sided IE treated with cloxacillin, of whom 53 (57%) had a vancomycin MIC < 1.5 µg/mL and 40 (43%) a vancomycin MIC ≥ 1.5 µg/mL. In-hospital mortality was 30% (n = 16/53) in patients with a low vancomycin MIC and 53% (n = 21/40) in those with a high vancomycin MIC (P = .03). No correlation was found between oxacillin MIC and vancomycin or daptomycin MIC. Logistic regression analysis showed that higher vancomycin MIC increased in-hospital mortality 3-fold (odds ratio, 3.1; 95% confidence interval, 1.2-8.2) after adjustment for age, year of diagnosis, septic complications, and nonseptic complicated endocarditis.

CONCLUSIONS:

Our results indicate that vancomycin MIC could be used to identify a subgroup of patients with methicillin-susceptible S. aureus IE at risk of higher mortality. The worse outcome of staphylococcal infections with a higher vancomycin MIC cannot be explained solely by suboptimal pharmacokinetics of antibiotics.

• Authors: Carlos Cervera, Ximena Castañeda, Cristina Garcia de la Maria, Ana del Rio, Asunción Moreno, Dolors Soy, Juan Manuel Pericas, Carlos Falces, Yolanda Armero, Manel Almela, Salvador Ninot, Juan Carlos Pare, Carlos A Mestres, Jose M Gatell, Francesc Marco, Jose M Miro, Hospital Clinic Endocarditis Study Group
• Journal: Clinical infectious diseases : an official publication of the Infectious Diseases Society of America (Clin Infect Dis) Vol. 58 Issue 12 Pg. 1668-75 (Jun 2014) ISSN: 1537-6591 [Electronic] United States
• PMID: 24647021 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: [email protected].

Chemical References

• Anti-Bacterial Agents
• Vancomycin
• Daptomycin
• Cloxacillin

Topics

• Adult
• Aged
• Anti-Bacterial Agents (pharmacology)
• Cloxacillin (pharmacology)
• Daptomycin (pharmacology)
• Endocarditis, Bacterial (drug therapy, microbiology)
• Female
• Hospital Mortality
• Humans
• Male
• Microbial Sensitivity Tests
• Middle Aged
• Retrospective Studies
• Staphylococcal Infections (drug therapy, microbiology)
• Staphylococcus aureus (drug effects)
• Survival Rate
• Vancomycin (pharmacology)