A 50-year-old man with fever and cough. Chest X-ray shows a right upper lobe consolidation with bulging of the horizontal fissure. Which organism is the most likely cause?
- A Streptococcus pneumoniae
- B Haemophilus influenzae
- C Klebsiella pneumoniae ✓
- D Mycoplasma pneumoniae
Correct answer: C. Klebsiella pneumoniae
Explanation
Klebsiella pneumoniae classically produces a lobar consolidation that bulges the fissure due to copious inflammatory exudate, most commonly in the upper lobes. Streptococcus pneumoniae causes typical lobar consolidation without fissure bulging. Haemophilus causes bronchopneumonia. Mycoplasma produces patchy interstitial infiltrates.
Reference: Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.