Lung abscess

Background

Microbiology

• Usually polymicrobial, including oral anaerobes
• Can also be monomicrobial, caused by Klebsiella, Staphylococcus aureus, Pseudomonas aeruginosa, Burkholderia pseudomallei (melioidosis), Pasteurella multocida, Streptococcus pyogenes, Haemophilus influenzae types b and c, Legionella species, Rhodococcus equi, Actinomyces species, and Nocardia species

Pathophysiology

• Mostly from chronic aspiration

Risk Factors

• Chronic aspiration from any etiology
  • Alcohol use disorder
  • Seizure disorder, stroke, drug overdose, general anesthesia
• Dysphagia or respiratory dysfunction from ALS, Parkinson disease, or stroke
• Tooth extraction

Differential Diagnosis

• See cavitary lung lesion

Management

• Unless clearly monomicrobial, should treat broadly and include good anaerobic coverage
  • Either a β-lactam plus metronidazole, or clindamycin
• Antibiotics usually for 6 to 8 weeks
• Can follow progress radiographically
• Rarely, surgical intervention