Make the Diagnosis: Red Eye, Green Discharge

(MedPage Today) -- Case Findings: A 17 year old male presents to your office with a red left eye. He says that last night he began having pain, redness, and irritation, and upon wakening today the symptoms were much more severe. At first the discharge was scant, but over the course of the day it worsened such that he has to continually wipe away "thick, green material. On exam, visual acuities are 6/6 in the right eye vs. 6/15 in the left eye. The right eye is not injected and normal on slit lamp examination. On examination of the left eye, there is severe injection and bogginess of the conjunctiva 360 degrees with abundant mucopurulent discharge. Peripheral corneal infiltrates and a 1+ cell reaction are also present. There is an enlarged preauricular lymph node on the left side. External appearance of the left eye is shown here. You suspect gonorrhea conjunctivitis and arrange for urgent antibiotic treatment. In addition to gonorrhea treatment, co-treatment of what infectious agent is recommended?