A 60-year-old smoker presents with fever, cough, and a right upper lobe cavitary lesion with an air-fluid level on CXR. Sputum culture grows anaerobic organisms. What is the most likely mechanism of infection?
- A Aspiration ✓
- B Hematogenous spread
- C Inhalation of aerosolized particles
- D Direct extension from liver abscess
Correct answer: A. Aspiration
Explanation
Aspiration pneumonia typically affects dependent segments (posterior segments of upper lobes or superior segments of lower lobes when supine) and is caused by anaerobic organisms from the oropharynx, leading to lung abscess with air-fluid level. Hematogenous spread causes multiple bilateral peripheral nodules. Inhalation causes TB or fungal infections. Direct extension from liver abscess would affect the right lower lobe.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.