mrcem2-1401

A 35-year-old traveler returns from a trip to Thailand with a painful, red right eye. The eye has been bothering him for the past two and a half weeks, and the onset of the irritation has been gradual. There has been mild mucopurulent discharge present in the eye for the past two weeks, and he states that he has to clean the eye regularly. On examination, you note the presence of right-sided, nontender pre-auricular lymphadenopathy. On further questioning, he admits to visiting a sex worker during his visit to Thailand.
Which of the following antibiotics would be most appropriate to prescribe for this patient?