Incidence and outcome of Staphylococcus aureus endocarditis-a 10-year single-centre northern European experience

Staphylococcus aureus is a leading cause of infective endocarditis. Little has been published on the outcome and epidemiology of S. aureus endocarditis (SAE) in the twenty-first century. Our aim was to evaluate the short-term and long-term outcome of SAE in Stockholm, Sweden, and assess its incidence over time. Patients treated for SAE from January 2004 through December 2013 were retrospectively identified at the Karolinska University Hospital. Clinical data were obtained from medical records and the diagnosis was verified according to the modified Duke criteria. Of 245 SAE cases, 152 (62%) were left-sided and 120 (49%) occurred in intravenous drug users. The calculated incidence in Stockholm County was 1.56/100 000 person-years, increasing from 1.28 in 2004-08 to 1.82/100 000 person-years in 2009-13 (p 0.002). In-hospital and 1-year mortality rates were 9.0% (22/245) and 19.5% (46/236), respectively. Age (OR 1.06 per year) and female sex (OR 3.0) were independently associated with in-hospital mortality in multivariate analysis. Involvement of the central nervous system (CNS) was observed in 30 (12%) patients, and valvular surgery was performed during hospitalization in 37 (15%). In left-sided endocarditis the strongest predictors for surgery were severe valvular insufficiency (OR 8.9), lower age (OR 1.07 per year) and no intravenous drug use (OR 10.7), and for CNS involvement lower age (OR 1.04 per year). In conclusion we noted low mortality, low CNS complication rate, and low valvular surgery frequency associated with SAE in our setting. The incidence was high and increased over time. The study provides an update on the outcome and epidemiology of SAE in the twenty-first century.