Pneumonia, Pediatric

Basics

Description

  • Infection of the lower respiratory tract are marked by the presence of fever, respiratory symptoms, and lung involvement (by physical examination and/or radiography)
  • Viral and bacterial causes are more prevalent during winter months and seasonal. Pathogen not confirmed in as many as 25% of cases
  • Common acquisition is by infectious droplet, contact with infected fomites, oropharyngeal aspiration and hematogenous
  • Risk factors include lower socioeconomic status, attendance at school/daycare, inadequate immunizations, and underlying medical conditions (particularly cardiopulmonary disease and sickle cell disease), exposure to tobacco smoke
  • As many as half of children under 5 yr of age with pneumonia require hospitalization

Etiology

  • <3 wk:
    • Group B Streptococcus species
    • E. coli and other enteric gram-negative organisms
    • Viruses (RSV, CMV, HSV)
    • L. monocytogenes
    • Maternal transmission: T. pallidum, Genital mycoplasma, or ureaplasma
  • 3 wk–3 mo:
    • Viruses (Parainfluenza virus, RSV)
    • Chlamydia trachomatis
    • S. pneumoniae
    • Bordetella pertussis
  • 3 mo–5 yr:
    • Viruses (predominate):
      • RSV
      • Parainfluenza virus
      • Influenza virus
      • Adenovirus
      • Rhinovirus
    • S. pneumoniae
    • H. influenza in unimmunized children
    • M. pneumoniae (>4 yr predominantly)
    • S. aureus
    • M. tuberculosis
  • >5 yr:
    • M. pneumoniae most common
    • Viral
    • S. pneumoniae
    • Chlamydia pneumoniae
  • Recent immigrants from developing countries:
    • M. tuberculosis, H. influenza, B. pertussis
  • Immunocompromised (eg, HIV, cancer):
    • P. carinii
    • Mycoplasma avium complex
    • M. tuberculosis
    • Klebsiella pneumoniae
    • Pseudomonas aeruginosa
  • Less common:
    • Fungal (coccidioidomycosis, histoplasmosis), Rickettsia (Q fever)
  • Identified patterns:
    • Lobar: S. pneumoniae
    • Bronchopneumonia: Sometimes associated with S. pyogenes and S. aureus
    • Necrotizing: Aspiration, S. pyogenes, S. pneumoniae, S. aureus
    • Caseating granuloma: M. tuberculosis
    • Interstitial/peribronchial with secondary parenchymal infection: Viral pneumonia with superinfection

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