mrcem2-1400

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 irritation has gradually increased. He has noticed mild mucopurulent discharge in the eye for the past two weeks and has been cleaning it regularly. During the examination, nontender pre-auricular lymphadenopathy is observed on the right side. Upon further questioning, he admits to engaging in sexual activity with a sex worker during his visit to Thailand.
What is the SINGLE most likely causative organism?