Impact of methicillin resistance on clinical features and outcomes of infective endocarditis due to Staphylococcus aureus

Background. This study sought to determine the impact of methicillin resistance on clinical features and outcomes in patients with Staphylococcus aureus (SA) infective endocarditis (IE). Methods: Retrospective chart review. Univariate and forward stepwise logistic regressions were conducted to determine which factors significantly affected death and systemic embolism. Results: From October 1995 to April 2002, 57 patients with a definite diagnosis of IE caused by SA were included: 28 cases of methicillin-sensitive SA infection and 29 methicillin-resistant SA (MRSA) infection. Patients with MRSA infection are more likely to have old age, underlying diseases, history of hospitalization within the last 6 months, nosocomial infection, and antibiotic use within the last 3 months. Patients with MRSA infection had clinical presentation of less systemic embolism and more sepsis and had a higher 3-month mortality rate. Methicillin resistance is an independent positive predictor of death and a negative predictor of systemic embolism. Conclusions: MRSA became a dominant cause of SA IE. Although it caused a lower incidence of systemic embolism, MRSA infection had a higher mortality rate because of sepsis.