A 32-year-old man comes to the office for evaluation of a one-day history of painful urination and urethral discharge. He is sexually active with two partners and only occasionally uses condoms. Temperature is 37.1 oC (98.8 oF), blood pressure is 133/81 mm Hg, pulse is 64/minute, and respiratory rate is 14/minute. Physical examination is remarkable for redness at the urethral meatus. A trace amount of clear, watery discharge is elicited with gentle compression of the glans. There is no inguinal lymphadenopathy.
Which of the following is most likely to be the first-line treatment for the cause of this patient’s symptoms?