A 26 year-old woman complains of left flank pain and fever for 2 days. She has a history of two episodes of urinary tract infections in the past three years treated with trimethoprim-sulfamethoxazole. She is married, sexually active and takes contraceptive pills. Her last menstrual period was 5 days ago. On physical examination, her pulse is 100/min., blood pressure is 120/80 and her temperature is 103 F. She has left costovertebral angle tenderness on palpation.
What is the best next step of management?
A-Admission to the intensive care unit (ICU)
B-Collection of urine and blood cultures
C-CT scan of abdomen and pelvis
D-MRI of the kidney
E-Administration of wide spectrum antibiotics