A Report on Severe Pneumonia Caused by <i>Chlamydia psittaci</i> Infection

Introduction: Chlamydia psittaci is a rare zoonotic pathogen that can cause severe pneumonia. Due to its lack of specific clinical manifestations and limited clinical treatment experience, it is often missed or misdiagnosed. Case Presentation: We report a case of C. psittaci infection detected by metagenomic next-generation sequencing (m-NGS), aiming to provide a clinical reference for diagnosis and treatment. The patient presented with severe pneumonia caused by C. psittaci infection. Upon admission, the patient's condition was urgent, with blood oxygen saturation dropping to 88% and abnormal increases in white blood cells, high-sensitivity C-reactive protein, and inflammatory factors. Chlamydia psittaci was detected from bronchoalveolar lavage fluid using m-NGS, leading to an adjustment in the selection of antibiotics. After 18 days of continuous treatment, the patient recovered well. Conclusions: Metagenomic next-generation sequencing has significant application value in the detection of rare pathogens. It can quickly and accurately obtain detection results, guide medication, and assist in better treating patients.