We suggest initial antibiotic management of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia with intravenous vancomycin or daptomycin (Grade 2C).
Persistent bacteremia may be due to a collection, the presence of a prosthetic device, or an endovascular source of infection that requires surgery. However, if antibiotic failure seems the most likely explanation and if the minimum inhibitory concentration (MIC) approaches the limit of the susceptible range (ie, 2 mcg/mL), vancomycin should be discontinued and therapy switched to an alternative agent.
If an alternative agent for treatment of MRSA bacteremia is needed due to vancomycin intolerance or inadequate response to treatment, we suggest treating with daptomycin or linezolid (Grade 2C). Susceptibility testing should be performed; in general, we favor daptomycin over linezolid.
We recommend initial antibiotic management of MRSA osteomyelitis with intravenous vancomycin or daptomycin (Grade 1C).
Vancomycin or daptomycin are the antibiotics of choice for treatment of invasive methicillin-resistant S. aureus (MRSA) infections. Patients with infections due to S. aureus with vancomycin minimum inhibitory concentration (MIC) at the high end of the susceptible range may not respond as well to therapy as those with a lower MIC. Alternative agents may be considered if there are adverse effects due to vancomycin or infection with a pathogen with inadequate susceptibility to vancomycin and evidence of a poor clinical response to therapy.
Given the array of relatively new alternative agents with activity against gram-positive organisms, further study is needed to determine the optimal use of these agents individually or in combination. Important considerations in selecting an alternative to vancomycin include baseline susceptibility testing prior to antibiotic administration and individual patient circumstances including the type of infection, underlying comorbidities, and other concurrent medications.