RespiratoryTier 2Disease (DEADMAN)

Lung abscess

Description

A localised, cavitating area of pulmonary necrosis containing pus, typically from aspiration or a complication of pneumonia

Epidemiology

Classic risk factors: impaired consciousness/swallowing (alcohol excess, seizures, stroke, anaesthesia), poor dental hygiene, oesophageal disease (reflux, achalasia) - all predisposing to aspiration of oropharyngeal flora

Aetiopathogenesis

Aspiration of anaerobic and mixed oral flora is the classic mechanism (right lower lobe most commonly affected given bronchial anatomy, or posterior segments of upper lobes if aspiration occurs supine)
Can also arise from bronchial obstruction (tumour, foreign body) causing post-obstructive infection, or haematogenous seeding (septic emboli - right-sided endocarditis, IVDU)

Diagnosis

CXR/CT shows a cavitating lesion with an air-fluid level
Sputum/blood cultures are often unrevealing for the true (often anaerobic, hard-to-culture) pathogens - clinical context (aspiration risk factors, indolent subacute course, foul-smelling sputum) is often more informative than microbiology

Management

Prolonged antibiotic course (weeks, often 4-6 weeks total, longer than typical pneumonia) covering anaerobes and mixed oral flora (e.g. amoxicillin-clavulanate or clindamycin)
Most resolve with antibiotics alone; surgical drainage/resection is reserved for failure of medical therapy, large abscesses, or suspicion of underlying malignancy/obstruction

Associations

Aspiration risk factors, poor dental hygiene, bronchial obstruction (exclude underlying malignancy, especially in older/smoking patients), septic pulmonary emboli

Natural history & complications

The prolonged treatment course reflects poor antibiotic penetration into necrotic/cavitating tissue; failure to respond or a new/unusual presentation should prompt reassessment for an obstructing lesion (especially in smokers)

6 more sections, plus exam facts

Premium unlocks every note across every specialty, and the full exam fact library behind it.

Get premium access