Question of the week: A 32-year-old woman with no notable medi | Daily Medical Info 4 Medics

Question of the week:
A 32-year-old woman with no notable medical history presents to the emergency department with pain in her back, left knee, and right ankle. She reports that the back pain began 3 weeks ago, frequently wakes her from sleep, is associated with stiffness in the morning, and improves with activity.
Her left knee and right ankle have become warm, swollen, and painful during the past week, impairing her ability to work. Naproxen at therapeutic levels provides only mild relief.
The patient also reports conjunctivitis and dysuria. She has multiple sexual partners who use condoms intermittently. She states that she does not experience fevers or rash.
Physical examination reveals moderate swelling in the left knee, warmth and redness of the right ankle, and tenderness at the right upper buttock.

Arthrocentesis of the knee effusion reveals cloudy synovial fluid containing 15,400 leukocytes per high-power field, with 85% neutrophils. Cultures of synovial fluid are negative.
Urine polymerase-chain-reaction testing is positive for Chlamydia trachomatis but negative for Neisseria gonorrhoeae.