Abstract:Objective To explore the clinical characteristics as well as early diagnosis and treatment of Chlamydia psittaci (C. psittaci) pneumonia. Methods 12 patients admitted in Pingxiang People's Hospital from February 2019 to February 2022 and diagnosed as C. psittaci pneumonia by metagenomic next-generation sequencing (mNGS) were selected, clinical data were analyzed and clinical characteristics as well as key points of diagnosis and treatment of the disease were summarized retrospectively. Results Most of the 12 patients with C. psittaci pneumonia had a history of contact with birds, pigeons or poultry (n=8), the main manifestations of the disease onset were high fever (n=12), general fatigue (n=12), cough (n=10), dyspnea (n=9) and headache (n=7), disease could rapidly progress to respiratory failure, septic shock, and even multiple organ failure. Laboratory tests showed that C-reactive protein increased in 12 patients, procalcitonin increased in 9 patients, blood routine lymphocytes all decreased, percentage of neutrophils increased in 10 patients, and white blood cells were normal in 9 patients. Chest CT showed inflammatory exudation and consolidation of one or both pulmonary lobes. Respiratory tract specimens or blood specimens were detected C. psittaci by mNGS, and the diagnosis was confirmed in combination with the contact history, clinical manifestations and imaging examination results. Quinolones were effective for treatment of 10 cases of C. psittaci pneumonia, and 1 patient who failed to use quinolones were treated with tetracyclines, and could still improve in a short time of disease condition. Conclusion C. psittaci pneumonia has obvious pulmonary symptoms, extrapulmonary symptoms are common and can progress rapidly, mNGS is an important detection technique for early diagnosis, which can reduce the delay of diagnosis. Patients with C. psittaci pneumonia recover well after timely initiation of targeted antimicrobial treatment.