Impact of Vancomycin Resistance on 30-Day Mortality in Solid Organ Transplant Recipients with Enterococcus faecium Bloodstream Infections: A Retrospective Cohort Analysis

<b>Background:</b><i>Enterococcus faecium</i> bloodstream infections (EF-BSI) cause significant morbidity and mortality in solid organ transplant (SOT) recipients, with the role of vancomycin resistance (VR) remaining controversial as an independent driver. <b>Methods:</b> This was a retrospective cohort study including SOT recipients with EF-BSI at our institution from 2019 to 2023. We used Cox proportional hazards regression to identify predictors of 30-day all-cause mortality. A time-dependent covariate was used to model the effects of receiving targeted, effective antibiotic therapy. <b>Results:</b> A total of 79 patients were included (26.6%, with VR). The overall 30-day mortality was 12.7% (10/79). In univariable analysis, septic shock (Hazard Ratio, HR: 17.1, 95% CI: 3.64-80.8, <i>p</i> < 0.001), the need for Continuous Venovenous Hemofiltration (HR: 6.40, 95% CI: 1.85-22.1, <i>p</i> = 0.003), and a Pitt Bacteremia Score ≥ 2 (HR: 5.17, 95%CI: 1.10-24.3, <i>p</i> = 0.038) were associated with increased mortality, while source control was protective (HR: 0.20, 95% CI: 0.05-0.76, <i>p</i> = 0.018). In the final multivariable model, only septic shock remained an independent predictor of 30-day mortality (HR: 11.4, 95% CI: 1.63-79.5, <i>p</i> = 0.014). VR was not significantly associated with mortality, though the confidence interval was wide and included clinically meaningful effects (HR: 2.07, 95% CI: 0.40-10.6, <i>p</i> = 0.4). <b>Conclusions:</b> In SOT recipients with EF-BSI, 30-day mortality is overwhelmingly driven by the host's physiological response, manifested as septic shock, rather than the VR profile of the pathogen. The early recognition of severe sepsis/septic shock and the aggressive implementation of supportive care and source control measures in this setting are crucial.