Vancomycin Versus Daptomycin for the Treatment of Methicillin-resistant Staphylococcus Aureus Bacteremia Due to Isolates With High Vancomycin Minimum Inhibitory Concentrations (MICs)

There is an increased failure rate for the treatment of Staphylococcus Aureus Bacteremia (SAB) with traditional doses of vancomycin, the standard of care for patients with MRSA bacteremia over the last 40 years. This has been largely attributed to isolates with increased resistance to vancomycin (increased MIC). Daptomycin is an antibiotic that was approved several years ago for the treatment of SAB and is being increasingly used for MRSA bacteremia due to isolates with increased MIC. Increased doses have been recommended for both of these drugs in the treatment of this infection without a trial demonstrating their relative efficacy or safety at higher doses. This study will randomize patients with SAB due to MRSA with an increased MIC to determine the relative efficacy and safety of vancomycin and daptomycin used at higher than traditional doses.

Inclusion Criteria:

• 18 years of age or older
• Signed informed consent
• All cases of suspected MRSA bacteremia as determined by a patient with at least one blood culture growing gram-positive cocci in clusters with a clinical syndrome consistent with true bacteremia including fever, hypothermia (temperature < 36.0º C), tachycardia (heart rate > 100 beats/minute), hypotension (systolic blood pressure < 90 mm Hg) or other clinical features of sepsis.
• All cases of right-sided native valve endocarditis due to MRSA
• Patients who are diagnosed with left-sided native valve endocarditis after randomization will be continued in the study
• Patients with MRSA bacteremia associated with infected foreign bodies, including vascular prostheses, orthopedic prostheses