Chlamydophila pneumoniae or psittaci

Chlamydophila pneumoniae or psittaci

 

Chlamydiae are obligate intracellular bacteria that infect humans and cause atypical pneumonias.

Epidemiology

  • Incidence – commonly implicated pathogen in atypical pneumonias
  • Age
    • Peak incidence is late childhood to young adulthood
      • By age 20, about 50% of young adults in the U.S. will have evidence of past infection
      • Reinfection throughout life is common
  • Transmission
    • Chlamydophila pneumoniae respiratory secretions
      • May produce epidemics in close quarter settings such as military barracks
    • Transmission to humans occurs from exposure to C. psittaci-infected birds via respiratory inhalation
      • Prolonged contact with the bird is not necessary for transmission
      • May be an occupationally related disease

Organism

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

Clinical Presentation

  • C. pneumoniae
    • Incubation – 7-10 days
    • Constitutional – resembles infections caused by Mycoplasma pneumoniae in that leukocytosis and fever are often lacking
    • Pulmonary – bronchitis, pneumonia
    • Upper respiratory tract – laryngitis, otitis media, sinusitis, pharyngitis
    • Dermatologic – erythema nodosum
    • Neurologic – meningitis (uncommon)
    • Cardiac – endocarditis, myocarditis (uncommon)
  • C. psittaci
    • Incubation – 7-14 days
    • Constitutional – fever, chills, headache, myalgias
    • Pulmonary – 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

Diagnosis

  • Confirmed by paired serology or PCR

Differential Diagnosis

  • Other bacterial or viral respiratory tract infections, viral hepatitis, whooping cough, myocardial infarction, polymyositis

Treatment

  • Antibiotic treatment is effective and curative

See Also