Lung Abscess

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Localised inflammation and necrosis (destruction) of lung tissue leading to pus formation. It is most commonly caused by aspiration of oral secretions by patients who have impaired consciousness.

Cause

  • Infection of lungs with pus forming organisms: e.g. Klebsiella pneumoniae, Staphylococcus aureus

Clinical features

  • Onset is acute or gradual
  • Malaise, loss of appetite, sweating with chills and fever
  • Cough with purulent sputum, foul-smelling breath (halitosis)
  • Chest pain indicates pleurisy
  • Finger clubbing

Complications

  • Pus in the pleural cavity (empyema)
  • Coughing out blood (haemoptysis)
  • Septic emboli to various parts of the body, e.g. brain (causing brain abscess)
  • Bronchiectasis (pus in the bronchi)

Differential diagnosis

  • Bronchogenic carcinoma
  • Bronchiectasis
  • Primary empyema communicating with a bronchus
  • TB of the lungs
  • Liver abscess communicating into the lung

Investigations

  • Chest X-ray
    • Early stages: Signs of consolidation
    • Later stages: A cavity with a fluid level
  • Sputum: For microscopy and culture and sensitivity

ManagementTreatment

  • Benzylpenicillin 1-2 MU IV or IM every 4-6 hours
    • Child: 50,000-100,000 IU/kg per dose (max: 2 MU)
  • Plus metronidazole 500 mg IV every 8-12 hours
    • Child: 12.5 mg/kg per dose

Once improvement occurs, change to oral medication and continue for 4-8 weeks

  • Metronidazole 400 mg every 12 hours
    • Child: 10 mg/kg per dose
  • Plus Amoxicillin 500 mg-1 g 8 hourly
    • Child: 25-50 mg/kg per dose for for 4-6 weeks
  • Postural drainage/physiotherapy
  • Surgical drainage may be necessary

Prevention

  • Early detection and treatment of pneumonia