Makindo Medical Notes

Poor prognosis with old age, severe comorbidities, immunosuppression, bronchial obstruction, and neoplasms.

About

• Lung abscess is a localized collection of pus within the lung parenchyma, leading to a cavity filled with necrotic debris.

Aetiology

• More common in the elderly, immunocompromised patients, and those prone to aspiration (e.g., those with neurological disorders, impaired consciousness).
• Frequent in alcoholics and IV drug users due to a higher risk of aspiration and infectious complications.

Classification

• Primary: Occurs in patients prone to aspiration or otherwise healthy individuals.
• Secondary: Due to an underlying disease, such as lung tumours, immune deficiencies (e.g., HIV/AIDS), or after organ transplantation.

Causes

• Aspiration Pneumonia, reflecting the flora of the oropharynx:
  • Anaerobic bacteria (e.g., Prevotella, Bacteroides, Fusobacterium, Peptostreptococcus).
  • In alcoholics with poor oral hygiene: Staphylococcus aureus, Streptococcus pyogenes, and Actinomyces.
• Other organisms: Staphylococcus aureus post-influenza, Klebsiella pneumoniae, Pseudomonas.
• Mycobacterium tuberculosis, Legionella, and fungal pathogens.
• Obstruction of bronchi due to tumours or inhaled foreign bodies.

Summary

Clinical

• Cough with foul-smelling sputum and halitosis.
• Fever, cachexia, weight loss, and finger clubbing.
• Night sweats, anaemia, and dyspnoea.
• Characteristic brown sputum in amoebic abscess.

Differential Diagnosis

• Squamous carcinoma with cavitation.
• Tuberculosis.
• Granulomatosis with polyangiitis (Wegener's).
• Pulmonary infarction.

Investigations

• Blood Tests: FBC (raised WCC), CRP, U&E, LFTs.
• CXR: Consolidation with cavitation and air-fluid level in a thin-walled cavity.
• CT Scan: HRCT chest for detailed anatomy and abscess definition.
• Bronchoscopy: Useful for diagnosing underlying causes like obstruction or neoplasm.
• Microbiology: Blood cultures, sputum cultures, bronchoalveolar lavage, and needle aspiration for specific pathogen identification.

Management: Take Early Expert Advice

• Postural drainage and chest physiotherapy to aid in the removal of purulent sputum.
• Oral and dental hygiene should be checked and maintained.
• Antibiotic therapy should be tailored to culture results, with IV therapy initially followed by oral therapy for several weeks. Choices include:
  • Co-amoxiclav 1.2 g TDS.
  • Clindamycin 600 mg QDS + Ciprofloxacin 750 mg BD.
  • IV Levofloxacin 500 mg BD and Metronidazole 500 mg TDS.
• Refer to a specialist if:
  • Fever persists after 10-14 days of treatment.
  • CXR indicates a non-resolving abscess.
• Indications for surgery include:
  • Failure to respond after 6 weeks of treatment.
  • Large abscess (>6 cm).
  • Haemorrhage or complications like empyema.
• Drainage may be achieved through needle aspiration or thoracotomy if necessary.
• Re-evaluate for treatment failure, considering:
  • Incorrect diagnosis or resistant organism.
  • Underlying conditions like malignancy or immune deficiency.
  • Complications such as empyema or haemorrhage.

References

• Guideline for the management of lung abscess in adults: Leeds