Soru

A 38-year-old man is evaluated in the hospital on day 3 of admission for high fever, chills, and progressive shortness of breath. He has a history of bipolar disorder, asthma, and intravenous drug use. On admission, blood cultures were drawn, and empirical intravenous vancomycin and cefepime were initiated. Today, the patient reports feeling persistently fatigued and depressed, stating he has been in a 'down state' for the past month. He is currently taking lithium. Temperature is $38.2^\circ\text{C}$ ($100.8^\circ\text{F}$), blood pressure is $110/70\text{ mm Hg}$, pulse is $105/\text{min}$, and respirations are $22/\text{min}$. Physical examination reveals a grade 3/6 holosystolic murmur at the left lower sternal border that increases in intensity with inspiration. Scattered bilateral lung crackles are present. Laboratory studies show:

An echocardiogram demonstrates a 1.5-cm mobile vegetation on the tricuspid valve with severe tricuspid regurgitation. Blood cultures from admission have grown methicillin-susceptible *Staphylococcus aureus* (MSSA). Which of the following is the most appropriate next step in management?