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Clinical features and prognostic factors of Chlamydia psittaci pneumonia: a retrospective study
Yanyan Li1, Hongyi Zhu2, Zijie Zhan3
1Department of Respiratory and Critical Diseases, The Affiliated Changde Hospital of Xiangya School of Medicine, Central South University, Changde, Hunan, China.
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.
Insights
Chlamydia psittaci pneumonia (CPP) often presents with non-specific symptoms. Severe cases show prolonged hospitalization, pleural effusion, and bilateral infiltrates, with D-dimer and lymphocyte percentage predicting severity.
Area of Science:
- Infectious Diseases
- Pulmonology
- Medical Diagnostics
Background:
- Chlamydia psittaci pneumonia (CPP) is a challenging diagnosis due to its frequent misdiagnosis and potential for severe outcomes.
- Understanding the clinical and imaging features of CPP is vital for timely detection and effective management.
Purpose of the Study:
- To investigate the clinical, laboratory, and imaging characteristics of Chlamydia psittaci pneumonia.
- To identify predictors of severe disease and evaluate treatment outcomes.
Main Methods:
- A retrospective analysis of 74 patients diagnosed with CPP using metagenomic (mNGS) and targeted next-generation sequencing (tNGS).
- Patients were classified into severe and non-severe groups based on community-acquired pneumonia severity criteria.
- Demographic, clinical, laboratory, and imaging data were collected and compared between groups.
Main Results:
- The study cohort had a median age of 60 years, with a male predominance and high prevalence of bird exposure (87.8%).
- Severe CPP cases exhibited longer hospitalization, increased pleural effusion, and bilateral lung involvement compared to non-severe cases.
- Elevated D-dimer and reduced lymphocyte percentage were identified as independent predictors of severe CPP.
Conclusions:
- Severe CPP is characterized by prolonged hospitalization, bilateral infiltrates, and pleural effusion.
- D-dimer levels and lymphocyte percentage serve as valuable prognostic markers for disease severity.
- Prompt antibiotic treatment (tetracyclines or quinolones) is effective, with critical need for respiratory support in severe instances.
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