High vancomycin minimum inhibitory concentration is associated with poor outcome in patients with methicillin-susceptible Staphylococcus aureus bacteremia regardless of treatment

Abstract

We retrospectively investigated the impact of high vancomycin minimum inhibitory concentration (MIC > 2 μg/ml) on the outcome of 53 patients with bacteremia caused by methicillin-susceptible Staphylococcus aureus (MSSA). Vancomycin MIC was determined by broth microdilution according to CLSI methods. The primary outcome was 30-day all-cause mortality from the date of the first positive blood culture. The mortality rate was 22.6% (12 of 53 patients). High vancomycin MIC (odds ratio (OR) = 9.3; 95% confidence interval (95% CI) = 1.31–63.20; p = 0.027), Charlson comorbidity index ≥ 3 (OR = 10.3; 95% CI = 1.3–102.04; p = 0.03), advanced age (OR = 35.8; 95% CI = 2.3–659.2; p = 0.01), and severe sepsis (OR = 8.5; 95% CI = 1.2–61.4; p = 0.03) were associated with mortality.

Keywords::

• Staphylococcus aureus
• bacteremia
• vancomycin
• mortality
• minimum inhibitory concentration

Acknowledgments

Supported by Plan Nacional de I+ D+ I 2008–2011 and Instituto de Salud Carlos III, Subdirección de Redes y Centros de Investigación Cooperativa, Ministerio de Economía y Competitividad, Spanish Network for Research in Infectious Diseases (REIPI RD12/0015) – co-financed by the European Development Regional Fund “A way to achieve Europe” ERDF.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsable for the content and writing of the paper.