A 31-year-old female with a history of injection drug use pr…

A 31-year-old female with a history of injection drug use presents with emergency department complaining of a 3-day history of fever, chills, loss of appetite and dyspnea on exertion. Transthoracic echocardiogram showed a vegetation present on the native tricuspid valve and blood culture reveal Staphylococcus aureus, susceptible to oxacillin.  She has her aortic valve replaced with prosthetic valve and she is successfully treated with nafcillinfor 6 weeks.  No however, 8 months later she presents again with these symptoms, and blood cultures confirm MSSA with a 4.5cm vegetation revealed on imaging confirming endocarditis.  How should you now treat this patient?