Acute infection and inflammation of the lungs alveoli.

There are two major types:

  • Bronchopneumonia: involves both the lung parenchyma and the bronchi. Common in children and the elderly
  • Lobar pneumonia: involves one or more lobes of the lung. Common in young people


Causative agents can be viral, bacterial or parasitic. Pathogens vary according to age, patient’s condition and
whether infection was acquired in the community or hospital (Gram negative are more common in hospital).

  • Neonates: group B streptococcus, Klebsiella, E.coli, Chlamydia and S. aureus
  • Children <5 years: Pneumococcus, Haemophilus influenzae, less frequently: S. aureus, M. catarrhalis, M. Pneumoniae,
    viruses (RSV, influenza, measles)
  • Adults and children >5 years: most commonly S.pneumoniae, followed by atypical bacteria, e.g.
    Mycloplasma pneumoniae, viruses
  • Immunosuppressed: Pneumocystis (in HIV infected)

Predisposing factors

  • Malnutrition
  • Old age
  • Immunosuppression (HIV, cancer, alcohol dependence)
  • Measles, pertussis
  • Pre existing lung or heart diseases, diabetes


If facilities are available

  • Do a chest X-ray and look for complications, e.g.
    • Pneumothorax, pyothorax
    • Pneumonitis suggestive of pneumocystis jiroveci pneumonia (PCP)
    • Pneumatocoeles (cavities filled with air) suggestive of staphylococcal pneumonia
  • Sputum: For Gram stain, Ziehl-Neelsen (ZN) stain, culture for AFB
  • Blood: Complete blood count