A lung abscess is a well-circumscribed infection within the lung parenchyma.

Pathophysiology

• most commonly forms secondary to aspiration pneumonia
  • poor dental hygiene, previous stroke and reduced consciousness are some of the risk factors for this
• other potential causes include:
  • haematogenous spread e.g. secondary to infective endocarditis
  • direct extension e.g. from an empyema
  • bronchial obstruction e.g. secondary from a lung tumour
• typically polymicrobial
• monomicrobial causes include:
  • Staphylococcus aureus
  • Klebsiella pneumonia
  • Pseudomonas aeruginosa

PC

• similar features to pneumonia but generally runs a more subacute presentation
  • symptoms may develop over weeks
  • systemic features such as night sweats and weight loss may be seen
• fever
• productive cough
  • often foul-smelling sputum
  • massive haemoptysis in a minority of patients
• chest pain
• dyspnoea

Examination:

• dull percussion and bronchial breathing
• clubbing may be seen

Investigation

• chest x-ray
  • fluid-filled space within an area of consolidation
  • an air-fluid level is typically seen
• sputum and blood cultures should be obtained

Management