This patient's vancomycin therapy should be discontinued, and treatment with an alternative agent, such as daptomycin, should be initiated. Although vancomycin is a reasonable choice for empiric therapy in patients suspected of having methicillin-resistant Staphylococcus aureus (MRSA) skin or soft tissue infection, it is only slowly bactericidal and generally less effective than agents more potently bactericidal against MRSA for treatment of bacteremia or infective endocarditis. The minimum inhibitory concentration (MIC) to vancomycin of the infecting organism is typically used to guide therapy. For isolates with a vancomycin MIC of 2 µg/mL or less, the patient's clinical response should determine whether to continue vancomycin or change to an alternative agent independent of the MIC. However, vancomycin is not recommended for bacteremia if the MIC to vancomycin is greater than 2 µg/mL. Therefore, continuing the current vancomycin dose in this patient would not be appropriate, and switching therapy to an alternative agent is indicated. If daptomycin is used, the MIC of the organism to daptomycin should also be verified to ensure susceptibility.

In patients in whom treatment with vancomycin for MRSA bacteremia is appropriate (vancomycin MIC of 2 µg/mL or less), the goal serum vancomycin trough level is 15 to 20 µg/mL. When the vancomycin trough level is within this range, as in this patient, increasing the vancomycin dose creates the risk of the trough level being higher than 20 µg/mL, which would increase the risks for adverse effects without providing additional clinical benefit. However, because the MIC of this organism to vancomycin is greater than 2 µg/mL, continuing dose-adjusted vancomycin would not be appropriate.

Adding rifampin to vancomycin has not been shown to improve clinical outcomes.