Vancomycin should be changed to a penicillinase-resistant semisynthetic penicillin antibiotic (oxacillin or nafcillin). The patient's blood cultures indicate infection with a methicillin-sensitive Staphylococcus aureus (MSSA) isolate. The β-lactam antibiotics are more rapidly bactericidal than vancomycin and are therefore the preferred class of antibiotics for treating serious S. aureus infections. Because this patient is not allergic to penicillin, oxacillin or nafcillin are the best choices. Vancomycin is associated with worse outcomes when used to treat MSSA infections. Empiric therapy with vancomycin is appropriate for patients in whom infection with methicillin-resistant S. aureus is a consideration. However, therapy should be modified as appropriate as soon as culture and antimicrobial susceptibility results are available.

Combination antimicrobial therapy (such as vancomycin and rifampin) for the treatment of S. aureus bacteremia does not improve clinical outcomes. Therefore, it would not be the most appropriate management choice for this patient.

Vancomycin therapy is monitored by serum trough levels, not serum peak levels. When vancomycin is used in the appropriate setting, the usual goal for the serum trough level is 15 to 20 µg/mL.

Definite or probable thrombosis occurs in approximately 70% of patients who have central venous catheter–associated S. aureus bacteremia. Imaging of the previous intravenous site is not necessary unless suspicion exists for suppurative thrombophlebitis (pain, swelling, palpable cord) or a fluid collection that would require drainage.