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Clinical characteristics and risk factors associated with severe community-acquired pneumonia infected by Chlamydia

Tingting Xu1, Qi Yuan1, Jiayue Wang1

  • 1Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.

Microbiology Spectrum
|September 24, 2025
PubMed

Insights

Severe psittacosis pneumonia is common, with higher inflammatory markers like neutrophil-to-lymphocyte ratio (NLR) indicating severity. NLR shows strong predictive value for identifying severe psittacosis pneumonia cases.

Area of Science:

  • Infectious Diseases
  • Pulmonology
  • Clinical Microbiology

Background:

  • Psittacosis pneumonia, caused by Chlamydia psittaci, can lead to severe respiratory illness.
  • Identifying predictors of severe disease is crucial for timely intervention and improved patient outcomes.

Purpose of the Study:

  • To describe the clinical features of psittacosis pneumonia.
  • To identify risk factors associated with severe psittacosis pneumonia.
  • To evaluate the predictive value of inflammatory markers for disease severity.

Main Methods:

  • Retrospective analysis of 24 psittacosis pneumonia patients diagnosed via metagenomic next-generation sequencing (mNGS).
  • Comparison of clinical and laboratory data between severe and non-severe psittacosis pneumonia groups.
  • Receiver operating characteristic (ROC) curve analysis to assess predictive values of NLR, PCT, and hs-CRP.

Main Results:

  • 33.3% of patients presented with severe psittacosis pneumonia.
  • Severe cases showed significantly higher white blood cells (WBCs), neutrophils, neutrophil-to-lymphocyte ratio (NLR), hypersensitive C-reactive protein (hs-CRP), procalcitonin (PCT), and fungal detection rates.
  • NLR demonstrated superior predictive value for severe disease compared to PCT and hs-CRP.

Conclusions:

  • Psittacosis pneumonia frequently leads to severe disease.
  • Elevated NLR is a significant indicator of severe psittacosis pneumonia.
  • NLR can serve as a valuable tool for early severity assessment and guiding optimal therapeutic strategies.
Keywords:
Chlamydia psittacimetagenomic next-generation sequencingneutrophil-to-lymphocyte ratioprocalcitoninsevere pneumonia

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