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Background Chlamydia psittaci pneumonia (CPP) is frequently misdiagnosed and can progress to severe illness. A deeper understanding of its clinical and imaging features is crucial for early detection and effective treatment. Methods This retrospective study analyzed 74 patients diagnosed with CPP via metagenomic (mNGS) and targeted next-generation sequencing (tNGS) between January 2022 and September 2025. Patients were categorized into severe ( n = 21) and non-severe ( n = 53) groups based on established criteria for severe community-acquired pneumonia. Data on demographics, clinical manifestations, laboratory findings, and imaging characteristics were collected and compared. Results The cohort had a median age of 60 years, with a male predominance (62.2%). A history of poultry/bird exposure was reported by 87.8% of participants. Common symptoms included fever (94.6%), cough (63.5%), and fatigue (29.7%), with no significant differences between groups. Hospitalization was significantly longer in the severe group (12.95 ± 6.08 days) than in the non-severe group (8.13 ± 3.30 days) ( p 0.001). Chest CT revealed consolidation and ground-glass opacities in all patients. Pleural effusion was significantly more common in the severe group (76.2% vs. 45.3%, p = 0.016), as was bilateral lung involvement (52.4% vs. 22.6%, p = 0.013). Multivariate analysis identified elevated D-dimer (OR = 2.737, p = 0.007) and reduced lymphocyte percentage (L%) (OR = 0.813, p = 0.026) as independent predictors of severe disease. ROC curve analysis showed an AUC of 0.765 for D-dimer and 0.739 for L% reduction. Following tetracycline or quinolone therapy, 94.6% of patients recovered, with an overall mortality rate of 5.4%. Conclusion Severe CPP is associated with prolonged hospitalization, bilateral pulmonary infiltrates, and pleural effusion. D-dimer and lymphocyte percentage are valuable prognostic indicators for disease severity. Early targeted antibiotic therapy is effective, but timely respiratory support is critical for severe cases.
Li et al. (Thu,) studied this question.