A 35-year-old woman is admitted with fever, chills, and low back pain for 5 days. Right renal area shows percussion tenderness. Urinalysis (UA): red blood cells (RBC) 5-6/HPF, white blood cell (WBC) count 20-30/HPF. Midstream urine culture shows Escherichia coli >10^5/ml. After 3 days of antibiotic therapy, her temperature normalizes. What should be done next?