BackgroundInvasive infections caused by Staphylococcus aureus have high clinical and epidemiological relevance. It is therefore important to monitor the S. aureus trends using suitable methods.AimThe study aimed to describe the trends of bloodstream infections (BSI) caused by meticillin-resistant S. aureus (MRSA) and meticillin-susceptible S. aureus (MSSA) in the European Union (EU) and the European Economic Area (EEA).MethodsAnnual data on S. aureus BSI from 2005 to 2018 were obtained from the European Antimicrobial Resistance Surveillance Network (EARS-Net). Trends of BSI were assessed at the EU/EEA level by adjusting for blood culture set rate (number of blood culture sets per 1,000 days of hospitalisation) and stratification by patient characteristics.ResultsConsidering a fixed cohort of laboratories consistently reporting data over the entire study period, MRSA percentages among S. aureus BSI decreased from 30.2% in 2005 to 16.3% in 2018. Concurrently, the total number of BSI caused by S. aureus increased by 57%, MSSA BSI increased by 84% and MRSA BSI decreased by 31%. All these trends were statistically significant (p < 0.001).ConclusionsThe results indicate an increasing health burden of MSSA BSI in the EU/EEA despite a significant decrease in the MRSA percentage. These findings highlight the importance of monitoring antimicrobial resistance trends by assessing not only resistance percentages but also the incidence of infections. Further research is needed on the factors associated with the observed trends and on their attributable risk.

Clinical microbiology Växjö Central hospital Växjö Sweden

Department of Epidemiology and Clinical Microbiology National Medicines Institute Warsaw Poland

Department of Microbiology 3rd Faculty of Medicine Charles University University hospital Kralovske Vinohrady and National Institute of Public Health Prague Czech Republic

Department of Microbiology and Infection Control University Hospital of North Norway Tromsø Norway

Division of Clinical Microbiology Department of Laboratory medicine Karolinska Institutet and Karolinska University Hospital Stockholm Sweden

European Centre for Disease Prevention and Control Solna Sweden

Health Protection Surveillance Centre Dublin Ireland

Healthcare associated infections surveillance of antimicrobial resistance and consumption Department for Infectious Disease Epidemiology Robert Koch Institute Berlin Germany

National Institute for Public Health and the Environment Bilthoven The Netherlands

National Institute of Public Health University of Ljubljana Slovenia

National reference laboratory for antibiotics National Institute of Public Health Prague Czech Republic

Norwegian Institute of Public Health Oslo Norway

Public Health Agency of Sweden Solna Sweden

Regional Agency for Health and Social Care of Emilia Romagna Bologna Italy

Research Group for Host Microbe Interaction Faculty of Health Sciences UiT The Arctic University of Norway Tromsø Norway

Sorbonne Universités UMR 1135 and APHP Pitié Salpêtrière hospital Laboratoire de Bactériologie Hygiène Paris France

World Health Organization Regional Office for Europe Copenhagen Denmark

Zagreb University Hospital for Infectious Diseases Zagreb Croatia

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