<i>Chlamydia psittaci</i> pneumonia in a patient using ustekinumab therapy for Crohn’s disease

This case highlights a potential association between ustekinumab and susceptibility to <i>C. psittaci</i>, a zoonotic intracellular pathogen. It underscores the importance of exposure history and considering atypical pathogens in immunocompromised patients. Clinicians should maintain vigilance for opportunistic infections in individuals receiving targeted biologic therapies.