A 57-year-old woman is evaluated for blood cultures growing yeast during long-term intravenous antibiotic therapy. She has completed 4 weeks of a planned 6-week course of intravenous antibiotics for methicillin-sensitive Staphylococcus aureus infective endocarditis. A peripherally inserted central venous catheter (PICC) was placed at the beginning of her treatment. She developed a high fever 3 days ago, and blood cultures drawn peripherally and through the catheter at that time grew Candida species; further identification is pending. Medical history is otherwise negative, and her only medication is nafcillin.
On physical examination, temperature is 37.8 °C (100.0 °F), blood pressure is 126/80 mm Hg, pulse rate is 82/min, and respiration rate is 16/min. The eye grounds are clear. Chest examination is unremarkable. Cardiac auscultation reveals a grade 2/6 crescendo-decrescendo murmur at the right upper sternal border. She has no spinal tenderness. The right brachial PICC site is without erythema, drainage, or tenderness.
In addition to continuing intravenous antibiotic therapy, which of the following is the most appropriate management?