Abstract:Objective To analyze the clinical features, diagnosis and treatment methods of Chlamydia psittaci (C. psittaci) pneumonia, and improve the understanding of the disease. Methods Clinical data of patients with C. psittaci pneumonia diagnosed with metagenomic next-generation sequencing (mNGS) in a hospital from September 2019 to August 2021 were retrospectively analyzed, clinical features, diagnosis and treatment of the disease was summarized. Results Among 8 patients, 7 were males and 1 was female, aged 45-83 years. All patients started with high fever, accompanied by cough, fatigue, and general muscle pain, 6 of whom had a definite history of poultry contact. All patients had increased C-reactive protein (CRP) and lactate dehydrogenase (LDH) as well as abnormal coagulation function; 5 patients had decreased lymphocyte count; 6 patients had increased alanine aminotransferase and aspartate aminotransferase as well as decreased blood sodium. Chest imaging showed that manifestation of unilateral lung was more common, lesions mainly occurred in the right lung (n=5), less in both lungs (n=1). Five patients showed lung consolidation with bronchial inflation sign, 1 patient was with lung consolidation, ground-glass opacity and cavity formation respectively. Seven patients showed congestion and edema of bronchial mucosa under bronchoscopy. Eight patients were clearly diagnosed as C. psittaci pneumonia by mNGS, and were treated with doxycycline, azithromycin and moxifloxacin, all patients were cured and discharged from hospital. Conclusion C. psittaci pneumonia is usually characterized by high fever with pulmonary consolidation patches, application of mNGS detection of bronchoalveolar lavage fluid of patient can quickly and accurately diagnose C. psittaci pneumonia. Early treatment with doxycycline, azithromycin or moxifloxacin is effective in C. psittaci pneumonia.