Intrapulmonary Abscess

Parenchymal necrosis with confined cavitation that results from a pulmonary infection

Aetiology

Primary Lung Abscess

Occurs without preexisting lung disease, most commonly due to aspiration of oropharyngeal contents.
Common risk factors:
Risk Factor
Mechanism
Alcohol intoxication
Impaired gag reflex
General anesthesia
Aspiration
Poor dental hygiene
Anaerobic oral flora
Seizures
Aspiration
Dysphagia
Aspiration risk
Altered consciousness
Loss of airway protection

Secondary Lung Abscess

Occurs due to underlying disease or obstruction.
Cause
Mechanism
Bronchial obstruction (tumor, foreign body)
Impaired drainage
Septic emboli
Hematogenous infection
Necrotizing pneumonia
Tissue destruction
Immunosuppression
Opportunistic infection
Bronchiectasis
Chronic infection
Pulmonary infarction
Tissue necrosis

Clinical presentation

  • Typically presents as a pneumonia that worsens despite treatment
  • Weight loss
  • Cough +/- sputum
  • Lethargy, tiredness, weakness

Investigations

  • CXR - walled cavity
  • CT can be used to differentiate between an empyema and an abscess

Management

Pharmacological Treatment

Empiric Antibiotic Therapy
Target anaerobes + aerobic bacteria.
Antibiotic
Dose (Adult)
Ampicillin–sulbactam
3 g IV every 6 hours
Clindamycin
600 mg IV every 8 hours
Piperacillin–tazobactam
4.5 g IV every 6 hours
Carbapenems
Severe infection
Oral Step-down Therapy
Drug
Dose
Amoxicillin-clavulanate
875/125 mg twice daily
Clindamycin
300–450 mg every 6 hours
Duration of Treatment
Typically 4–6 weeks or until radiological resolution.

Interventional Treatment

Indications:
  • Abscess >6 cm
  • No response to antibiotics
  • Suspicion of obstruction
Procedures:
  • Percutaneous Drainage
  • Bronchoscopic Drainage
  • Surgical Resection (rare)