Comparison of morbidity and mortality after bloodstream infection with vancomycin-resistant versus -susceptible Enterococcus faecium: A nationwide cohort study in Denmark, 2010-2019.

(unstructured)The emergence of bloodstream infections (BSI) caused by vancomycin-resistant Enterococci (VRE) has caused concern. Nonetheless, it remains unclear whether these types are associated with an excess risk of severe outcomes when compared with infections caused by vancomycin-susceptible Enterococci (VSE). This cohort study included hospitalised patients in Denmark with Enterococcus faecium positive blood cultures collected between 2010 and 2019 identified in the Danish Microbiology Database. We estimated the 30-day hazard ratio (HR) of death or discharge among VRE compared to VSE patients adjusted for age, sex, and comorbidity. The cohort included 6,071 patients with E. faecium BSI (335 VRE, 5,736 VSE) among whom VRE increased (2010-13, 2.6%; 2014-16, 6.3%; 2017-19; 9.4%). Mortality HR (1.08, 95%CI 0.90-1.29; 126 VRE, 37.6%; 2,223 VSE, 37.0%) or discharge HR (0.89, 95%CI 0.75-1.06; 126 VRE, 37.6%; 2,386 VSE, 41.6%) was not different between VRE and VSE overall. However, VRE patients had excess mortality in 2014 only (HR 1.87, 95% CI 1.18-2.96). There was no interaction between time from admission to BSI (1-2, 3-14, and >14 days) and HR of death (P = 0.14) or discharge (P = 0.45) after VRE compared to VSE, despite this time was longer for VRE patients (17 vs. 10 days for VSE, p < 0.0001). In conclusion, VRE BSI was not associated with excess morbidity and mortality. The fact that excess mortality was observed in 2014 only may be attributed to improved diagnostic- and patient-management practices after 2014, thus reducing time to appropriate antibiotic therapy. The high level of mortality after E. faecium BSI warrants further study.