Chlamydophila species

  • Diagnosis
  • Background
  • Lab Tests
  • References
  • Related Topics

Indications for Testing

  • C. pneumoniae – atypical pneumonia presentation
  • C. psittaci – atypical pneumonia and history of bird exposure

Laboratory Testing

  • Chlamydophila pneumoniae infection (CDC, 2014)
  • Psittacosis (CDC, 2014)
  • Initial testing
    • CBC with differential
  • Serology
    • Atypical pneumonia presentation
      • Order C. pneumoniae, M. pneumoniae and Legionella pneumophila concurrently; routine diagnostic tests to identify etiologic agent of outpatient pneumonia in adults is optional (Infectious Disease Society of America/American Thoracic Society)
      • Confirmed by paired serology for C. pneumoniae (four-fold elevation)
      • PCR – much more sensitive than culture and serology
      • Culture – difficult to grow atypical agents; positive culture confirms diagnosis
    • Suspicion for C. psittaci
      • Order antibody panel if suspicious of C. psittaci
      • Performed using complement fixation, microimmunofluorescence, enzyme immunoassay

Imaging Studies

  • Chest x-ray – no distinctive chest x-ray pattern

Differential Diagnosis

Chlamydophila is a genus of bacteria in the Chlamydiaceae family that causes atypical pneumonias, which may become life threatening.

Epidemiology

  • Incidence
  • Age
    • C. pneumoniae – peak incidence is late childhood to young adulthood
      • ~50% of young adults in the U.S. will have evidence of past infection by age 20
      • Reinfection throughout life is common
  • Transmission
    • C. pneumoniae – respiratory secretions
      • May produce epidemics in close-quarter settings such as military barracks, prisons
    • C. psittaci – respiratory inhalation of dried secretions during exposure to infected birds (zoonoses)
      • Does not require prolonged contact with infected bird
      • May be an occupation-related disease

Organism

  • C. psittaci and C. pneumoniae are obligate, intracellular, gram-negative bacteria

Clinical Presentation

  • C. pneumoniae
    • Incubation – 7-10 days
    • Constitutional – leukocytosis and fever are often lacking; may resemble Mycoplasma pneumoniae infections
    • Pulmonary – cough, bronchitis, pneumonia, exacerbations of chronic bronchitis and asthma
    • Upper respiratory tract – laryngitis, otitis media, sinusitis, pharyngitis
    • Dermatologic – erythema nodosum
    • Neurologic – meningitis (uncommon)
    • Cardiac – endocarditis, myocarditis (uncommon)
  • C. psittaci
    • Incubation – 5-19 days
    • Constitutional – fever, chills, headache, myalgias
    • Pulmonary – dry cough, pleural rub, rales, dyspnea, pneumonia
    • Gastrointestinal – diarrhea, nausea, anorexia, abdominal pain
    • Hepatitic – hepatitis
    • Dermatologic – faint macular rash may occur (Horder spots), erythema multiforme, erythema nodosum
    • Neurologic – cranial nerve palsies, cerebellar involvement, transverse myelitis, meningitis
    • Cardiac – endocarditis, myocarditis, pericarditis
Tests generally appear in the order most useful for common clinical situations. Click on number for test-specific information in the ARUP Laboratory Test Directory.

Chlamydia pneumoniae by PCR 0060715
Method: Qualitative Polymerase Chain Reaction

Recommended Use 

Confirm C. pneumoniae as infectious agent in nasal wash, nasopharyngeal aspirate, bronchoalveolar lavage (BAL) or pleural fluid

More sensitive than IFA and culture

Chlamydia Antibody Panel, IgG & IgM by IFA 0065100
Method: Semi-Quantitative Indirect Fluorescent Antibody

Recommended Use 

Differentiate between Chlamydophila species (C. psittaci, C. pneumoniae)

Differentiate early IgM response to infection from persistent low-level titer

Because of cross-reactivity, a C. pneumoniae-specific reaction will exhibit titers two-fold or greater than C. trachomatis or C. psittaci serology

Limitations 

Anti-chlamydial IgM antibody is very cross-reactive and will often represent titers to multiple, non-infecting chlamydial species

Follow-up 

If results are equivocal, retest sera 2-3 weeks after first test

Mycoplasma pneumoniae Antibodies, IgG & IgM 0050399
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Recommended Use 

Testing to evaluate for acute mycoplasma infection

Legionella pneumophila Antigen, Urine 0070322
Method: Qualitative Enzyme-Linked Immunosorbent Assay

Recommended Use 

Rapid diagnostic test for Legionella

General References

Blasi F, Tarsia P, Aliberti S. Chlamydophila pneumoniae. Clin Microbiol Infect. 2009; 15(1): 29-35. PubMed

Burillo A, Bouza E. Chlamydophila pneumoniae. Infect Dis Clin North Am. 2010; 24(1): 61-71. PubMed

Cunha BA. The atypical pneumonias: clinical diagnosis and importance. Clin Microbiol Infect. 2006; 12 Suppl 3: 12-24. PubMed

Forgie S, Marrie TJ. Healthcare-associated atypical pneumonia. Semin Respir Crit Care Med. 2009; 30(1): 67-85. PubMed

Johansson N, Kalin M, Tiveljung-Lindell A, Giske CG, Hedlund J. Etiology of community-acquired pneumonia: increased microbiological yield with new diagnostic methods. Clin Infect Dis. 2010; 50(2): 202-9. PubMed

Kumar S, Hammerschlag MR. Acute respiratory infection due to Chlamydia pneumoniae: current status of diagnostic methods. Clin Infect Dis. 2007; 44(4): 568-76. PubMed

Villegas E, Sorlózano A, Gutiérrez J. Serological diagnosis of Chlamydia pneumoniae infection: limitations and perspectives. J Med Microbiol. 2010; 59(Pt 11): 1267-74. PubMed

Wolf J, Daley AJ. Microbiological aspects of bacterial lower respiratory tract illness in children: atypical pathogens. Paediatr Respir Rev. 2007; 8(3): 212-9, quiz 219-20. PubMed

References from the ARUP Institute for Clinical and Experimental Pathology®

Kendall BA, Tardif KD, Schlaberg R. Chlamydia trachomatis L serovars and dominance of novel L2b ompA variants, U.S.A. Sex Transm Infect. 2014; 90(4): 336. PubMed

Medical Reviewers

Delgado, Julio, MD, MS, Head, Histocompatibility and Immunogenetics; Section Chief, Immunology Division at ARUP Laboratories; Associate Professor of Clinical Pathology, University of Utah

Fisher, Mark A., PhD, D(ABMM), Medical Director, Bacteriology and Antimicrobials at ARUP Laboratories; Assistant Professor of Clinical Pathology, University of Utah

Hillyard, David R., MD, Medical Director, Molecular Infectious Diseases at ARUP Laboratories; Professor of Clinical Pathology, Adjunct Professor of Biology, University of Utah

Last Update: August 2016

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