Soru

A 52-year-old woman presents to the outpatient clinic with a 2-day history of dysuria, urinary frequency, and suprapubic discomfort. She has a history of a mechanical mitral valve replacement for which she takes warfarin. Her most recent international normalized ratio (INR), checked 2 days ago, was 2.8. She has no fever, chills, vaginal discharge, or flank pain. Vital signs are temperature 37.1°C (98.8°F), heart rate 82/min, blood pressure 124/78 mm Hg, and respiratory rate 14/min. Physical examination reveals mild suprapubic tenderness but no costovertebral angle tenderness. Urinalysis shows positive leukocyte esterase, positive nitrites, and $>50$ white blood cells/hpf. She has no known drug allergies and her renal function is normal. Which of the following is the most appropriate pharmacologic management for this patient?