ObjectiveTo investigate the clinical characteristics of severe Chlamydia abortus pneumonia complicated by acute respiratory distress syndrome (ARDS). MethodsSix cases of severe Chlamydia abortus pneumonia with ARDS admitted to the Department of Critical Care Medicine, Quanzhou First Hospital Affiliated to Fujian Medical University, from January 2021 to June 2025 were enrolled. The clinical features were analyzed based on demographic data, laboratory tests, imaging findings, and other clinical information. ResultsAll six patients were diagnosed via metagenomic next-generation sequencing (mNGS). The median age was 63.5 years (range, 42~73), and four patients had a history of exposure to poultry or animals. Initial symptoms were nonspecific, including fever and cough. All patients developed high fever and dyspnea, with a peak body temperature of 39.7°C (range, 39.2~41.1°C). The median time from symptom onset to dyspnea was 2 days (range, 1~3). Four patients presented with extrapulmonary symptoms. Elevated white blood cell count was observed in three patients; all six patients had an increased neutrophil percentage and a decreased lymphocyte percentage. Three patients had mild anemia and mild thrombocytopenia. All six patients showed markedly elevated procalcitonin, interleukin-6, and C-reactive protein. Elevated liver enzymes and creatine kinase levels were observed in all six patients to varying degrees. Four patients had mild hyponatremia, two had hypokalemia, and five had varying degrees of elevated serum creatinine. Chest CT findings included consolidation involving single or multiple lobes, with or without small pleural effusions. All patients met the diagnostic criteria for severe ARDS and received invasive mechanical ventilation via endotracheal intubation as well as prone positioning. After targeted therapy, five patients improved markedly, whereas one female patient died of secondary infection. ConclusionsSevere community-acquired pneumonia caused by Chlamydia abortus can lead to ARDS and/or multiorgan involvement. In patients with severe pneumonia and a history of exposure to sick poultry or aborted animals, Chlamydia abortus infection should be considered. mNGS plays a critical role in early diagnosis and the transition to targeted therapy. Appropriate antimicrobial therapy combined with rational respiratory support strategies may contribute to favorable patient outcomes.