Makindo Medical Notes

Related Subjects: | Assessing Breathlessness | Fever - Pyrexia of unknown origin

⚠️ Poor Prognosis: Advanced age, severe comorbidities, immunosuppression, bronchial obstruction, and underlying malignancy worsen outcomes.

📖 About

• Lung abscess = localised collection of pus within the lung parenchyma → cavity filled with necrotic debris.
• Classic association: aspiration pneumonia in alcoholics or those with impaired consciousness.
• Pathology: tissue necrosis, liquefaction, and cavity formation with air–fluid level on imaging.

🧬 Aetiology

• More common in the elderly, immunocompromised, and aspiration-prone patients (neurological disease, reduced GCS, alcohol, drugs).
• High risk in alcoholics & IV drug users due to aspiration and secondary infection.

📂 Classification

• Primary: Occurs in otherwise healthy but aspiration-prone patients.
• Secondary: Arises from underlying pathology (e.g., lung cancer, immune suppression, organ transplant).

🦠 Causes

• Aspiration Pneumonia → mixed anaerobes from oropharynx (Prevotella, Bacteroides, Fusobacterium, Peptostreptococcus).
• Alcoholics with poor oral hygiene → Staph. aureus, Strep. pyogenes, Actinomyces.
• Other: Klebsiella, Pseudomonas, TB, Legionella, fungi.
• Bronchial obstruction (tumour, foreign body).
• Septic emboli from right-sided endocarditis or thrombophlebitis.

🩺 Clinical Features

• Cough with foul-smelling purulent sputum + halitosis.
• Fever, weight loss, night sweats, cachexia.
• Clubbing in chronic cases.
• Amoebic abscess → characteristic “anchovy sauce” brown sputum.

🧾 Differential Diagnosis

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

🔎 Investigations

• Bloods: FBC (neutrophilia), CRP, U&E, LFTs.
• CXR: Consolidation with cavity and air–fluid level.
• CT chest (HRCT): Defines abscess and rules out underlying malignancy.
• Bronchoscopy: For obstruction / malignancy suspicion.
• Microbiology: Blood/sputum cultures, BAL, needle aspiration.

💊 Management (Specialist Input Early)

• Supportive: Postural drainage, physiotherapy, oral hygiene.
• Antibiotics (IV → PO for weeks):
  • Co-amoxiclav 1.2 g TDS.
  • Clindamycin 600 mg QDS + Ciprofloxacin 750 mg BD.
  • Levofloxacin 500 mg BD + Metronidazole 500 mg TDS.
• Escalate:
  • If fever persists >10–14 days, re-image.
  • Non-resolving abscess → surgical referral.
  • Surgery if >6 cm, haemorrhage, or empyema.
• Drainage: Needle aspiration / thoracotomy if needed.

📚 References

• Leeds Guideline: Lung Abscess in Adults