A 54-year-old male with Crohn’s disease, undergoing ustekinumab therapy, presented with fever, cough, and dyspnea. Initial chest X-ray showed infiltrates, and he was admitted for community-acquired pneumonia. Despite broad-spectrum antibiotics, his condition worsened. Bronchoalveolar lavage and sputum analysis, including PCR, ultimately identified Chlamydia psittaci as the causative agent. The patient improved significantly after treatment with doxycycline. This case highlights the importance of considering atypical pathogens like C. psittaci in immunocompromised patients, even those on biologics like ustekinumab, and the utility of specific diagnostic methods when empiric therapy fails.
Key note: Immunocompromised patients on biologics require a high index of suspicion for atypical infections.