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

We retrospectively investigated the impact of high vancomycin minimum inhibitory concentration (MIC > 2 mu g/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.