A bacterial respiratory pathogen that is a frequent cause of community-acquired pneumonia in children and adults.
An obligate intracellular bacterium that can only be isolated in tissue culture, although culture is not widely available. Infection can be diagnosed using nucleic acid amplification tests and two FDA-approved commercial assays are now available.
Pneumonia due to Chlamydia pneumoniae cannot be differentiated clinically from pneumonia due to other atypical organisms, especially Mycoplasma pneumoniae.
Treatment with macrolides, fluoroquinolones, or tetracyclines appears equally effective.
History and exam
Key diagnostic factors
- presence of risk factors
Other diagnostic factors
- illness in other family members
- wheezes on chest auscultation
- pleuritic chest pain
- dullness to percussion/reduced air entry/decreased tactile fremitus
1st investigations to order
- chest x-ray
- WBC count with differential
Investigations to consider
- C pneumoniae culture of nasopharynx, sputum, or pleural fluid
- C pneumoniae antibody
- Nucleic acid amplification tests for C pneumoniae
Margaret R. Hammerschlag, MD
Professor of Pediatrics and Medicine
Division of Pediatric Infectious Diseases
SUNY Downstate Medical Center
MRH is an author of a number of references cited in this monograph.
Yuji Oba, MD, FCCP
Associate Professor of Clinical Medicine
Division of Pulmonary/Critical Care Medicine
School of Medicine
University of Missouri-Columbia
YO declares that he has no competing interests.
Sebastian Johnston, MB, BS, PhD, FRCP
Professor of Respiratory Medicine
Honorary Consultant Physician in Allergy and Respiratory Medicine
Department of Respiratory Medicine
Imperial College School of Medicine
SJ has received fees for speaking, and research and consultant fees from Sanofi Pasteur, Aventis, GlaxoSmithKline, AstroZeneca, Merck, Pfizer, Centocor, and Synergen.
- Coronavirus disease 2019 (COVID-19)
- Mycoplasma pneumoniae pneumonia
- Pneumonia, bacterial
- Diagnosis and treatment of adults with community-acquired pneumonia
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