Methicillin-resistant Staphylococcus aureus infective endocarditis

Methicillin was introduced in 1959 to treat penicillin-resistant S. aureus infection, however Methicillin-resistant S. aureus (MRSA) was reported 2 years later (1). The most common organism identified in acute infective endocarditis (AIE) is still S. aureus associated with increased hospital mortality, morbidity and hospitalization. In Germany the proportion of MRSA among S. aureus microbiologic examinations was 1.1% in 1990 and dramatically increased to 17.5% by 2001 and reached 21.9% in 2009 (2). Due to the biofilm in AIE, adequate treatment is challenging, including appropriate antibiotic therapy. To improve outcome of AIE early adequate antibiotic therapy is needed, however vancomycin has a decrease microbe clearance and poor clinical response compared with β-lactam agents in Methicillin-susceptible S. aureus. Today, several reports on clinical failures in MRSA with vancomycin were documented even at MICs <2.0 μg/ml. Current guidelines recommend higher trough vancomycin of 10-20 μg/ml, which will lead to increase complications such as nephrotoxicity (3). Therefore more effective alternative antibiotic treatment is needed to treat MRSA endocarditis and reach sufficient into the biofilm (4). This overview reports recent developments to improve MRSA endocarditis treatment.