1. A 20-year-old female presents with a two day history of dysuria and increased urinary frequency. She states that she was recently married and was not sexually active prior to the marriage. Physical exam reveals a temperature of 100.7 蚌 with normal vital signs. Gynecological exam reveals no evidence of discharge, vaginitis, or cervicitis. Urinalysis reveals 14 white blood cells per high-powered field with many gram-negative rods. The most appropriate therapy would be