A 24-year-old woman presents with right knee pain, swelling, and difficulty walking for the past 2 days. She also reports multiple joint pains and swelling. The patient has recently had multiple sexual partners and has used condoms inconsistently. On examination, she has a swollen, tender, erythematous knee joint with limited range of motion, along with tender wrist and ankle joints and several small pustules on her palms.
Laboratory results:
WBC: 12,500/mm³ (elevated)
CRP: Elevated
Synovial fluid analysis:
WBC 50,000/mm³, predominantly neutrophils
Gram stain: No organisms seen
Culture: Pending
What is the next best step in management?