A 28-year-old woman with known Crohn's disease (ileocolonic, inflammatory, moderate-to-severe) has failed azathioprine after 9 months. She is now started on adalimumab (anti-TNF). Before starting biologic therapy, the most important infection screening is:

• A Hepatitis C antibody and HIV test
• B Stool culture for Clostridium difficile and CMV
• C Tuberculosis screening (IGRA/TST), hepatitis B serology, and varicella status ✓
• D Chest X-ray only

Explanation

Before initiating biologic therapy (anti-TNF, vedolizumab, ustekinumab) or immunomodulators, current guidelines mandate screening for latent tuberculosis (IGRA or tuberculin skin test; IGRA preferred in BCG-vaccinated patients), hepatitis B surface antigen and core antibody (to prevent HBV reactivation), and assessment of varicella and other live vaccine statuses. Active TB must be treated before starting anti-TNF agents. Prophylactic antiviral therapy is initiated in HBsAg-positive patients. This screening is mandatory per ECCO and AGA guidelines.

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

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Written and medically reviewed by the StethoPrep medical team.