Association between ratio of area under the concentration-time curve to minimum inhibitory concentration of vancomycin and clinical outcomes in Enterococcus faecium bacteremia

The purpose of this study was to evaluate the relationship between the treatment resolution of Enterococcus faecium bacteremia and the pharmacodynamic targets of vancomycin. This is a retrospective single-center cohort study involving patients with E. faecium bacteremia on vancomycin therapy hospitalized between January 2010 and December 2021. The average vancomycin area under the concentration-time curve (AUC)(0 -24) was computed using the Bayesian approach. The minimum inhibitory concentration (MIC) was determined using the broth microdilution method, and The AUC(24)/MIC value over the initial 24-48 h of therapy was calculated. We assessed 30-day mortality, as the primary outcome. Classification and regression tree analysis (CART) was used to identify the vancomycin AUC(24)/MIC target associated with 30-day mortality. Eighty-seven patients with E. faecium bacteremia were included in this study, with 14 (16.1%) being non-survivors. In the CART analysis, vancomycin AUC/MIC >= 414.3 was associated with a higher treatment success. In multivariate analysis, an AUC/MIC >= 414.3 was a significant factor for treatment success (adjusted odds ratio = 17.5, 95% confidence interval, 3.7-83.9). Our findings suggest that a target vancomycin AUC/MIC >= 414.3 is a good prognostic indicator and could be useful for treatment monitoring of E. faecium bacteremia.