Increasing proportion of vancomycin resistance among enterococcal bacteraemias in Switzerland: A 6-year nation-wide surveillance, 2013 to 2018

Background: Vancomycin-resistant enterococci (VRE), mostly Enterococcus faecium, are multidrug-resistant microorganisms that can cause nosocomial infections. VRE has increased throughout many European countries, but data from Switzerland are scarce. Aim: The aim of this work was to characterise the epidemiology of enterococcal bacteraemias in Switzerland with a focus on VRE. Methods: In this observational study, we retrospectively investigated bacteraemias from 81 healthcare institutions from January 2013 to December 2018 using data from the Swiss Centre for Antibiotic Resistance. Only the first blood isolate with E. faecalis or E. faecium from an individual patient was considered. We analysed the annual incidences of enterococcal bacteraemias and determined the proportion of VRE over time. We also assessed epidemiological factors potentially associated with VRE bacteraemia. Results: We identified 5,369 enterococcal bacteraemias, of which 3,196 (59.5%) were due to E. faecalis and 2,173 (40.5%) to E. faecium. The incidence of enterococcal bacteraemias increased by 3.2% per year (95% confidential interval (CI):1.6–4.8%), predominantly due to a substantial increase in E. faecalis bacteraemic episodes. Vancomycin resistance affected 30 (1.4%) E. faecium and one E. faecalis bacteraemic episodes. Among all E. faecium bacteraemias, the proportion of vancomycin-resistant isolates increased steadily from 2013 to 2018 (2% per year; 95%CI:1.5–2.9%). No independent epidemiological factor for higher prevalence of vancomycin-resistant E. faecium bacteraemias was identified. Conclusions: Vancomycin-resistant E. faecium bacteraemias remain infrequent in Switzerland. However, an important increase was observed between 2013 and 2018, highlighting the need for implementing active surveillance and targeted prevention strategies in the country.