A 34-yeаr-оld оtherwise heаlthy wоmаn presents to your primary care office with a 2-day history of dysuria, urinary urgency, and urinary frequency that has progressed to fever, chills, nausea, and left-sided flank pain. She is alert, well hydrated, and able to tolerate oral fluids. Vital signs are as follows: temperature 100.8°F, blood pressure 118/72 mmHg, heart rate 92 bpm, respiratory rate 16 breaths/min, and oxygen saturation 99% on room air. Physical examination demonstrates left costovertebral angle tenderness. Urinalysis reveals positive nitrites, positive leukocyte esterase, pyuria, bacteriuria, and WBC casts. A urine culture is obtained before initiating treatment. Which of the following is the most appropriate antibiotic selection?