Several days after an episode of urethritis, a 28-year-old man develops acute pain and swelling of the left knee. On physical examination, the knee is swollen and is warm and tender to the touch. No other joints seem to be affected. Laboratory examination of fluid aspirated from the left knee joint shows numerous neutrophils. A Gram stain of the fluid shows gram-negative intracellular diplococci. No crystals are seen. Which infectious agent is most likely responsible for this condition?
□ (A) Borrelia burgdorferi
□ (B) Treponema pallidum
□ (C) Neisseria gonorrhoeae
□ (D) Staphylococcus aureus
□ (E) Haemophilus influenzae
