A 59-year-old patient is admitted with mitral valve endocarditis. Blood cultures grow methicillin-susceptible Staphylococcus aureus, and nafcillin is initiated.

Four days after admission, the patient develops dyspnea, hypoxia, and hypotension. The patient's vital signs include a temperature of 36.8 °C, heart rate of 87/minute, BP of 92/68 mm Hg, respiratory rate of 28/minute, and SpO₂ of 98% with high-flow nasal oxygen at 40 L/minute and FiO₂ of 0.6. On examination, jugular venous pressure is 12 mm Hg, and the patient has bibasilar crackles and 2+ lower extremity edema bilaterally. An echocardiogram reveals a 7-mm vegetation on the anterior mitral valve leaflet and severe mitral regurgitation.