A 62-year-old man undergoes transurethral resection of the prostate (TURP) for benign prostatic hyperplasia. Two days post-operatively, he develops fever, dysuria, and suprapubic tenderness. A urine culture grows Enterococcus faecalis, resistant to trimethoprim and cephalosporins, but sensitive to amoxicillin and nitrofurantoin. He is able to take oral medication. What is the most appropriate oral antibiotic choice?