To investigate the clinical characteristics, diagnosis, and treatment course of a patient with lung malignancy complicated by severe pneumonia caused by Chlamydia psittaci infection.

The clinical data of a patient with lung malignancy complicated by Chlamydia psittaci induced severe pneumonia, admitted to the Department of Respiratory and Critical Care Medicine of the General Hospital of Western Theater Command on December 3, 2023, were retrospectively analyzed. Relevant literature was also reviewed to summarize the clinical features and management strategies for severe Chlamydia psittaci pneumonia.

A 60-year-old female patient presented with high fever, cough, and sputum production. After admission, she received non-invasive ventilation and broad-spectrum antibiotic therapy with meropenem. However, her condition deteriorated rapidly, and her oxygen saturation remained difficult to maintain even after endotracheal intubation and invasive mechanical ventilation. Subsequently, bronchoscopy and bronchoalveolar lavage (BAL) were performed under extracorporeal membrane oxygenation (ECMO) support. Metagenomic next-generation sequencing (mNGS) of the BAL fluid identified Chlamydia psittaci as the causative pathogen. Targeted antimicrobial therapy with doxycycline, azithromycin, and levofloxacin was sequentially administered, leading to clinical improvement. Ultimately, the patient underwent thoracoscopic radical resection for lung cancer. Postoperative genetic testing of the specimen revealed a deletion variation on exon 19 of EGFR. Adjuvant therapy with icotinib was initiated, resulting in complete remission.

mNGS technology can effectively improve the detection rate of Chlamydia psittaci and prevent further clinical deterioration. For patients with severe Chlamydia psittaci pneumonia, early respiratory support combined with precise targeted antimicrobial therapy is crucial for improving patient prognosis.