• An acute LRTI with fever, symptoms and signs in the chest and abnormalities on the chest X ray
• Incidence 5-11/1000
  • 70% over 65
• Mortality 21% in hospital
• Pneumonia can be classified as lobar pneumonia or bronchopneumonia
  • Depending on the main site of inflammatory response - this is secondary to infection

Bronchopneumonia

• 1 or more lobes
  • Bronchioles and adjancent alveoli
• Primary infection centres around the bronchi
  • Spreads to involve adjacent alveoli, which become consolidated
• Initial consolidation is patchy, involving lobules, but can become confluent and involve lobes if untreated
• Lesions are initially focal, involving one or more lobules. Bronchioles become inflamed and filled with pus, cilliated epitehlium is destroyed and vessels become congested
• Most common in infancy and old age due to immobility and retention of secretions
  • Most commonly affects the lower lobes due to the effect of gravity

Lobular pneumonia

• Entire lobe affected

• Organisms gain entry to distal air spaces rather than colonising bronchi

  • Rapid spread of infection through alveolar air spaces

• Macroscopically, the whole lobe becomes consolidated and airless

• Ppts are normally adults, and become severly ill with associated bacteremia

• Inflammatory exudate within the alveolar air spaces causes 'consolidation'

  • Renders the infected areas of the lung macroscopically solid

• Consolidation CLASSICALLY occurs in bacterial pneumonias

  • Viral infections generally spare the air spaces and affect the interstitium, causing interstium pneumonia or pneumonitis

  

  

• 4 stages of inflammation