Vancomycin resistance predicts increased mortality in patients with Enterococcus faecium bloodstream infections: a six-year experience at a large tertiary care Italian hospital

Objectives To report on clinical outcomes associated with vancomycin-resistant Enterococcus faecium (VRE) Bloodstream infections (BSIs) observed during a 6-year period at a hospital from an area of high VRE endemicity. Material and methods Retrospective study of patients with VRE and/or vancomycin-susceptible E. faecium (VSE) BSI in an Italian tertiary care hospital from January 2018 to December 2023. Results The cohort included 116 VRE and 225 VSE BSIs. The baseline characteristics were comparable in both populations. Almost half VRE population (53/116, 46%) received no or ineffective empiric therapy against VRE. A targeted effective therapy was initiated with a mean delay of 2.2, ± 0.4 days in the VRE patients and of 1.2 ± 0.1 days (P < 0.01) in the VSE patients. The univariate analysis showed higher rates of septic shock in the VRE group (60% versus 40%, P < 0.01), and the 30-day mortality rate was 29% and 46% in VSE and VRE BSIs, respectively (P < 0.01). By multivariate analysis, Sequential Organ Failure Assessment score (HR 1.25; 95% CI 1.19–1.31, P < 0.001), Charlson Comorbidity Index (HR 1.14; 95% CI 1.06–1.22, P = 0.001) and vancomycin resistance (HR 1.93; 95% CI 1.33–2.82, P = 0.001) resulted as independent predictors of mortality. The statistical association was confirmed in a sensitive analysis after removing polymicrobial BSI. Conclusions E. faecium BSIs confirmed to be associated with high mortality rate, especially in fragile patients. Moreover, vancomycin resistance is an independent mortality factor. Further studies are needed to identify patients at higher risk for E. faecium BSI.