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ORIGINAL RESEARCH article

Front. Med.

Sec. Infectious Diseases: Pathogenesis and Therapy

Volume 12 - 2025 | doi: 10.3389/fmed.2025.1653394

Comparison of Clinical Features between Chlamydia psittaci and Legionella

Provisionally accepted
Jiamei  ChenJiamei Chen1Libing  YangLibing Yang1Yuni  LiuYuni Liu2Yongzhong  LiYongzhong Li1Zhou  JianliangZhou Jianliang3Jin  WangJin Wang1*Yixiang  ZhengYixiang Zheng4
  • 1Department of Infectious Diseases, Hunan University of Medicine General Hospital, Huaihua, China
  • 2Department of Gastroenterology, Yiyang Third People’s Hospital, Yiyang, Hunan Province, People’s Republic of China, Yiyang, China
  • 3Department of Intensive Care Medicine, Hunan University of Medicine General Hospital, Huaihua, China
  • 4The First Affiliated Hospital of Xiangya Hospital, Changsha, China

The final, formatted version of the article will be published soon.

Objectives: Traditional diagnostic methods have difficulty distinguishing between Chlamydia psittaci (C. psittaci) pneumonia and Legionella pneumonia (L. pneumonia). This study aims to delineate the differences between C. psittaci pneumonia and L. pneumonia. Methods: This retrospective analysis included 71 cases of C. psittaci pneumonia and 21 cases of L. pneumonia, all confirmed via next-generation sequencing (NGS). We systematically collected and compared data on clinical characteristics, laboratory findings, chest CT imaging, bronchoscopic observations, and prognostic outcomes between the two groups. Results: In the C. psittaci pneumonia cohort, 64 patients (91.4%) had a opportunity to contact with poultry, with a maximum temperature of mean 39.6°C. Additionally, 23 patients (32.4%) experienced dyspnea, and 57 patients (80.3%) exhibited relative bradycardia. Compared to patients with L. pneumonia, those with C. psittaci pneumonia had lower leukocyte counts, neutrophil counts, mononuclear cell counts, systemic inflammatory response index (SIRI), and urea levels, while lymphocyte-to-monocyte ratio (LMR), glutamic-pyruvic transaminase (ALT), glutamic oxaloacetic transaminase (AST), and creatine kinase (CK) levels were elevated. Next-generation sequencing (NGS) plays a crucial role in the early diagnosis of infectious pathogens. multivariate analysis revealed differences in underlying diseases,residing in countryside,relative bradycardia, and LMR between the two groups. Conclusion: Several characteristics aid in differentiating C. psittaci pneumonia from L.pneumonia, including exposure to poultry, relative bradycardia, some infection indicators, ALT, AST, and CK. NGS addresses the limitations of traditional diagnostic methods. The early application of NGS facilitates the diagnosis of atypical pneumonia. Multivariate regression analysis suggested that underlying diseases,residing in countryside,relative bradycardia, and LMR is significant in differentiating C. psittaci pneumonia and L. pneumonia.

Keywords: Chlamydia psittaci pneumonia, Legionella pneumonia, Clinical features, next-generation sequencing (NGS), diagnosis

Received: 24 Jun 2025; Accepted: 20 Oct 2025.

Copyright: © 2025 Chen, Yang, Liu, Li, Jianliang, Wang and Zheng. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Jin Wang, 13607410137@163.com

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