Even with prompt treatment, Staphylococcus aureus Infective Endocarditis (IE) continues to be associated with significant morbidity and mortality indicating a need for new therapeutic approaches. In vitro, daptomycin is rapidly bactericidal, with concentration-dependent killing, and MIC90 of 0.5 g/ml for S. aureus; in clinical studies, daptomycin appears to be well tolerated and can be administered once every 24 hours by i.v. infusion. These characteristics suggest it should be clinically and microbiologically effective in the treatment of serious S. aureus infections, including IE and bacteremia