Pneumonia, Pediatric

Basics

Infection of the lower respiratory tract infections diagnoses 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
Spread is by droplet exposure, oropharyngeal aspiration and hematogenous
Lower socioeconomic status (household crowding), attendance at school/daycare, inadequate immunizations, and exposure to tobacco smoke are significant risk factors
As many as half of children under 5 years of age with pneumonia require hospitalization

<3 wk:
- Group B Streptococcus species
- Enteric gram-negative organisms
- Viruses (RSV, CMV, HSV)
- L. monocytogenes
- Maternal transmission: T. pallidum, Genital mycoplasma or ureaplasma
3 wk–3 mo:
- Chlamydia trachomatis
- Viruses (Parainfluenza virus, RSV)
- S. pneumoniae
- Bordetella pertussis
3 mo–5 yr:
- Viral (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
- Chlamydophila pneumoniae
Recent immigrants from developing countries:
- Mycoplasma tuberculosis
- H. influenza
- B. pertussis
Immunocompromised (e.g., 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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