eMedicine Specialties > Pulmonology > Infectious Lung Diseases

Chlamydial Pneumonias: Differential Diagnoses & Workup

Author: Yuji Oba, MD, FCCP, Associate Professor of Clinical Medicine, Division of Pulmonary, Critical Care, and Environmental Medicine, University of Missouri Health Care
Coauthor(s): Vamsi P Guntur, MD, MSc, Assistant Professor of Clinical Medicine, Division of Pulmonary, Critical Care and Environmental Medicine, University of Missouri
Contributor Information and Disclosures

Updated: Oct 15, 2008

Differential Diagnoses

Influenza
Psittacosis
Legionnaires Disease
Q Fever
Mycoplasma Infections
Tuberculosis
Pneumonia, Bacterial
Tularemia
Pneumonia, Fungal
Pneumonia, Viral

Other Problems to Be Considered

C trachomatis infant pneumonia
Respiratory syncytial virus infection
Bordetella pertussis infection
Infection with other respiratory viruses

Workup

Laboratory Studies

  • C psittaci
    • Single serum titers are insensitive and nonspecific. Confirmation with paired acute and convalescent sera is advised.
    • According to CDC case definitions,3 a confirmed case involves (1) isolation of the organism by culture or (2) compatible clinical illness with a 4-fold rise in complement-fixing (CF) or microimmunofluorescence (MIF) antibodies against C psittaci (to a reciprocal titer of 32 or greater by paired sera at least 2 wk apart) or detection of immunoglobulin M (IgM) titer of 16 or greater against C psittaci by MIF . Serologic tests are preferred because culture is difficult and hazardous.
    • The CDC defines a probable case as a compatible clinical illness (1) that is epidemiologically linked to a confirmed case or (2) that has a single antibody titer of 32 or greater by MIF or CF after the onset of symptoms. The CDC accepts human specimens for the diagnosis of C psittaci infection (404-639-3563).10
    • A CF test can cross-react with C pneumoniae and C trachomatis. MIF and polymerase chain reaction assays can be used to distinguish C psittaci infection from infection with other chlamydial species.
    • A third serum sample may be necessary to confirm the diagnosis because antibiotic treatment can delay or diminish the antibody response. All serologic tests should be performed simultaneously at the same laboratory.
  • C pneumoniae
    • The commonly used serologic criteria are an IgM titer exceeding 1:16 or a 4-fold increase in the immunoglobulin G (IgG) titer by MIF.11 (Note: A CF test cross-reacts with C psittaci.) However, serologic testing is poorly standardized and studies have shown poor reproducibility.12,13,14  In addition, the presence of a single elevated IgG titer may not be reliable because elderly patients can have persistently elevated IgG titers due to repeated infections. 
    • The absence of detectable antibodies several weeks after the onset of infection does not exclude a diagnosis of acute C pneumoniae pneumonia because the IgM antibody response may take as long as 6 weeks and the IgG antibody response may take as long as 8 weeks to appear in primary infections.
    • In some laboratories, a polymerase chain reaction with pharyngeal swab, bronchoalveolar lavage, sputum, or tissue can be used to seek C pneumoniae -specific DNA. It is the most promising rapid test but remains experimental.
    • Cell culture with oropharyngeal swabs is probably the best test, but it requires specialized culture techniques. It is performed only in research laboratories.
  • C trachomatis
    • Clinical findings suggest the diagnosis; the presence of chlamydial inclusions or elementary bodies on Giemsa-stained smears of the conjunctivae or nasopharynx confirms the diagnosis.
    • Testing may show findings of elevated antichlamydial IgM titer. Peripheral eosinophilia and elevated serum immunoglobulin levels are characteristic.

Imaging Studies

  • Chest radiographs
    • C psittaci: Consolidation in a single lower lobe is the most common finding. However, various findings have been observed, including patchy reticular infiltrates radiating from the hilum, a diffuse ground-glass appearance, and a miliary pattern. Pleural effusions are evident in as many as 50% of cases; however, the effusions are usually small and do not cause symptoms.
    • C pneumoniae: Chest radiographs most commonly show a single subsegmental infiltrate that is mainly located in the lower lobes. Extensive consolidation is rare, although acute respiratory distress syndrome has been reported. No radiographic findings are characteristic. Residual changes can be observed even after 3 months. Pleural effusion occurs in 20-25% of cases.
    • C trachomatis: Chest radiographs show bilateral interstitial infiltrates with hyperinflation.8

Other Tests

  • C pneumoniae: The white blood cell count is usually not elevated in C pneumoniae infection. Alkaline phosphate levels may be elevated.
  • C trachomatis: Screen parents for chlamydia and other sexually transmitted diseases.

Histologic Findings

Intra-alveolar inflammation with a milder degree of interstitial reaction is a characteristic pathologic finding in the lungs. Alveolar-lining cells contain intracytoplasmic inclusions.

More on Chlamydial Pneumonias

Overview: Chlamydial Pneumonias
Differential Diagnoses & Workup: Chlamydial Pneumonias
Treatment & Medication: Chlamydial Pneumonias
Follow-up: Chlamydial Pneumonias
References
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References

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  2. Ewig S, Torres A. Is Chlamydia pneumoniae an important pathogen in patients with community-acquired pneumonia?. Eur Respir J. May 2003;21(5):741-2. [Medline]. [Full Text].

  3. Centers for Disease Control and Prevention. Compendium of measures to control Chlamydia psittaci infection among humans (psittacosis) and pet birds (avian chlamydiosis), 2000. MMWR Recomm Rep. Jul 14 2000;49:3-17. [Medline]. [Full Text].

  4. Fine MJ, Smith MA, Carson CA, Mutha SS, Sankey SS, Weissfeld LA, et al. Prognosis and outcomes of patients with community-acquired pneumonia. A meta-analysis. JAMA. Jan 10 1996;275(2):134-41. [Medline].

  5. File TM Jr, Tan JS, Plouffe JF. The role of atypical pathogens: Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella pneumophila in respiratory infection. Infect Dis Clin North Am. Sep 1998;12(3):569-92, vii. [Medline].

  6. Marrie TJ, Peeling RW, Reid T, De Carolis E. Chlamydia species as a cause of community-acquired pneumonia in Canada. Eur Respir J. May 2003;21(5):779-84. [Medline]. [Full Text].

  7. Tipple MA, Beem MO, Saxon EM. Clinical characteristics of the afebrile pneumonia associated with Chlamydia trachomatis infection in infants less than 6 months of age. Pediatrics. Feb 1979;63(2):192-7. [Medline].

  8. Edelman RR, Hann LE, Simon M. Chlamydia trachomatis pneumonia in adults: radiographic appearance. Radiology. Aug 1984;152(2):279-82. [Medline].

  9. Cunha BA. The atypical pneumonias: clinical diagnosis and importance. Clin Microbiol Infect. May 2006;12 Suppl 3:12-24. [Medline].

  10. Centers for Disease Control and Prevention. Case definitions for infectious conditions under public health surveillance. MMWR Recomm Rep. May 2 1997;46:1-55. [Medline].

  11. Dowell SF, Peeling RW, Boman J, Carlone GM, Fields BS, Guarner J, et al. Standardizing Chlamydia pneumoniae assays: recommendations from the Centers for Disease Control and Prevention (USA) and the Laboratory Centre for Disease Control (Canada). Clin Infect Dis. Aug 15 2001;33(4):492-503. [Medline]. [Full Text].

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  13. Littman AJ, Jackson LA, White E, Thornquist MD, Gaydos CA, Vaughan TL. Interlaboratory reliability of microimmunofluorescence test for measurement of Chlamydia pneumoniae-specific immunoglobulin A and G antibody titers. Clin Diagn Lab Immunol. May 2004;11(3):615-7. [Medline].

  14. Mandell LA, Wunderink RG, Anzueto A, Bartlett JG, Campbell GD, Dean NC, et al. Infectious Diseases Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia in adults. Clin Infect Dis. March 2007;44:Suppl 2:S27-72. [Medline]. [Full Text].

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  16. Grayston JT. Infections caused by Chlamydia pneumoniae strain TWAR. Clin Infect Dis. Nov 1992;15(5):757-61. [Medline].

  17. Ieven MM, Hoymans VY. Involvement of Chlamydia pneumoniae in atherosclerosis: more evidence for lack of evidence. J Clin Microbiol. Jan 2005;43(1):19-24. [Medline].

  18. Andersen P. Pathogenesis of lower respiratory tract infections due to Chlamydia, Mycoplasma, Legionella and viruses. Thorax. Apr 1998;53(4):302-7. [Medline].

  19. Johnston WB, Eidson M, Smith KA, Stobierski MG. Compendium of chlamydiosis (psittacosis) control, 1999. Psittacosis Compendium Committee, National Association of State Public Health Veterinarians. J Am Vet Med Assoc. Mar 1 1999;214(5):640-6. [Medline].

  20. Massachusetts General Hospital. Case records of the Massachusetts General Hospital. Weekly clinicopathological exercises. Case 16-1998. Pneumonia and the acute respiratory distress syndrome in a 24-year-old man. N Engl J Med. May 21 1998;338(21):1527-35. [Medline].

  21. Schneeberger PM, Dorigo-Zetsma JW, van der Zee A, van Bon M, van Opstal JL. Diagnosis of atypical pathogens in patients hospitalized with community-acquired respiratory infection. Scand J Infect Dis. 2004;36(4):269-73. [Medline].

  22. Telfer BL, Moberley SA, Hort KP, Branley JM, Dwyer DE, Muscatello DJ, et al. Probable psittacosis outbreak linked to wild birds. Emerg Infect Dis. Mar 2005;11(3):391-7. [Medline].

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Further Reading

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Keywords

chlamydial pneumonia, psittacosis , ornithosis, Chlamydophila pneumoniae, Chlamydia pneumoniae, C pneumoniae, Chlamydophila psittaci, Chlamydia psittaci, C psittaci, Chlamydophila trachomatis, Chlamydia trachomatis, C trachomatis, Chlamydophila pneumoniae pneumonia, Chlamydophila trachomatis pneumonia, Taiwan acute respiratory pneumonia, TWAR pneumonia, parrot fever, avian chlamydiosis

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Contributor Information and Disclosures

Author

Yuji Oba, MD, FCCP, Associate Professor of Clinical Medicine, Division of Pulmonary, Critical Care, and Environmental Medicine, University of Missouri Health Care
Yuji Oba, MD, FCCP is a member of the following medical societies: American College of Chest Physicians and American Thoracic Society
Disclosure: Nothing to disclose.

Coauthor(s)

Vamsi P Guntur, MD, MSc, Assistant Professor of Clinical Medicine, Division of Pulmonary, Critical Care and Environmental Medicine, University of Missouri
Vamsi P Guntur, MD, MSc is a member of the following medical societies: American Association for Cancer Research, American College of Chest Physicians, American College of Physicians, American Thoracic Society, and Society of Critical Care Medicine
Disclosure: Nothing to disclose.

Medical Editor

Helen M Hollingsworth, MD, Director, Adult Asthma and Allergy Services, Associate Professor, Department of Internal Medicine, Division of Pulmonary and Critical Care, Boston Medical Center
Helen M Hollingsworth, MD is a member of the following medical societies: American Academy of Allergy Asthma and Immunology, American College of Chest Physicians, American Thoracic Society, and Massachusetts Medical Society
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Om Prakash Sharma, MD, FRCP, FCCP, DTM&H, Professor, Department of Medicine, Division of Pulmonary and Critical Care Medicine, University of Southern California Keck School of Medicine
Om Prakash Sharma, MD, FRCP, FCCP, DTM&H is a member of the following medical societies: American Academy of Allergy Asthma and Immunology, American College of Chest Physicians, American College of Physicians, American Federation for Medical Research, American Osler Society, American Thoracic Society, New York Academy of Medicine, and Royal Society of Medicine
Disclosure: Keck School of Medicine, USC None None

CME Editor

Timothy D Rice, MD, Associate Professor, Departments of Internal Medicine and Pediatrics and Adolescent Medicine, Saint Louis University School of Medicine
Timothy D Rice, MD is a member of the following medical societies: American Academy of Pediatrics and American College of Physicians
Disclosure: Nothing to disclose.

Chief Editor

Zab Mosenifar, MD, Director, Division of Pulmonary and Critical Care Medicine, Director, Women's Guild Pulmonary Disease Institute, Executive Vice Chair, Department of Medicine, Cedars Sinai Medical Center; Professor of Medicine, David Geffen School of Medicine at UCLA
Zab Mosenifar, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, American Federation for Medical Research, and American Thoracic Society
Disclosure: Nothing to disclose.

 
 
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