Rapid diagnosis of pulmonary Chlamydia psittaci infection using metagenomic next-generation sequencing: a case report and literature review

Objectives To present the clinical diagnosis and treatment of a case of Chlamydia psittaci pneumonia, review relevant literature, assess the diagnostic value of metagenomic next-generation sequencing (mNGS) in this condition, and enhance clinical understanding of the disease.Methods A case of Chlamydia psittaci pneumonia treated at Tai'an Central Hospital, affiliated with Qingdao University, was analyzed. The terms "Chlamydia psittaci" and "pneumonia" were used to search PubMed for case reports published from 2019 to 2024, and 41 selected cases were summarized and analyzed.Results The patient, a 61-year-old female, was diagnosed with Chlamydia psittaci pneumonia through mNGS of alveolar lavage fluid. Following treatment with levofloxacin and doxycycline, she was discharged from the hospital. A review of the literature identified 41 related cases. The primary clinical manifestations of Chlamydia psittaci pneumonia included fever (100 %), cough (51.2 %), headache (17.1 %), and dyspnea (14.6 %). A history of poultry exposure was noted in 90.2 % of patients. Chest CT imaging revealed bilateral lung involvement in 10 patients (24.3 %), pleural effusion in seven patients (17.1 %), and unilateral lung inflammation in 31 patients (75.6 %). The diagnosis was achieved by mNGS in 38 patients. Most were treated with doxycycline, minocycline, or moxifloxacin, with favorable outcomes. Improvement was observed in 40 patients (97.6 %) following timely and accurate treatment.Conclusions In summary, mNGS is a primary method for detecting Chlamydia psittaci clinically. The main treatment for infections caused by this pathogen involves tetracyclines or combinations of tetracyclines and fluoroquinolones.