aetiology and pathogenesis

Last reviewed 01/2018

Infection and necrotic tissue are critical to the development of a lung abscess.

The organisms most commonly involved are aerobic and anaerobic streptococci, Staphylococcus aureus and a variety of different gram-negative organisms. Anaerobes normally found in the oral cavity occur exclusively in 60% of cases - including Bacteroides, Fusobacterium, and Peptococcus.

Organisms may be introduced through:

  • aspiration
  • antecedent primary bacterial infection
  • septic emboli
  • neoplasia
  • other factors

Primary cryptogenic lung abscesses describe those for which no cause can be ascertained.