A 24-year-old sexually active woman presents with fever, migratory polyarthralgia for one week, and now a hot swollen right wrist. Examination reveals scattered painless pustules on the forearms. Joint aspirate shows WBC 40,000 cells per microlitre. Which organism is the most likely cause?

• A Neisseria gonorrhoeae ✓
• B Staphylococcus aureus
• C Streptococcus pyogenes
• D Haemophilus influenzae

Explanation

Disseminated gonococcal infection classically produces a biphasic illness of migratory polyarthralgia and tenosynovitis with sparse pustular skin lesions, followed by localisation into a purulent monoarthritis, most often the wrist, ankle or knee. The pustules are the discriminating finding against Staphylococcus aureus, which causes a more abrupt monoarthritis without rash. Aspirate cultures are often negative in gonococcal arthritis, so urethral, cervical and pharyngeal samples aid diagnosis.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.