A man presents with purulent penile discharge about a week after exposure. The most likely diagnosis is infection with which organism?

• A. Chlamydia trachomatis
• B. Herpes simplex virus
• C. Human papillomavirus
• D. Gonorrhea

Answer: (D)

Purulent urethral discharge after a new exposure is most characteristic of gonorrhea, caused by Neisseria gonorrhoeae. In men, this infection typically presents within about a week with a thick, pus-like discharge and discharge accompanied by painful urination as the bacteria invade the urethral mucosa and trigger pus formation. Microscopy of the discharge can reveal Gram-negative intracellular diplococci, and testing with nucleic acid amplification from urine or urethral swab confirms the diagnosis.

Chlamydia trachomatis can cause urethritis too, but its discharge is often less purulent or mucopurulent rather than frank purulence, and herpes simplex virus causes painful genital ulcers rather than a purulent discharge. Human papillomavirus presents with warts, not purulent discharge.