Protracted and recurrent methicillin-resistant Staphylococcus aureus bacteremia despite defervescence with vancomycin therapy

Methicillin-resistant Staphylococcus aureus (MRSA) bacteremia persisted for 46 days in a 63-year-old patient and recurred over 98 days in a 79-year-old patient, despite vancomycin therapy. Although the fever resolved, patient 1 developed a spinal epidural abscess 38 days after beginning therapy and patient 2 sustained multiple relapses. A time-kill study demonstrated a reduced vancomycin killing rate in both isolates when compared to the killing rate of a control MRSA strain. The bacteremia persisted after increasing the vancomycin dose to achieve trough levels of 15-20 micrograms; it cleared after adding gentamicin. These cases illustrate that MRSA bacteremia may persist during vancomycin therapy despite resolution of fever and may lead to delayed complications, and that adding gentamicin may be necessary for ultimate clearance of the bacteremia.