A 30-year-old woman with fever and productive cough for 4 days. Chest X-ray shows homogeneous opacity in the right lower zone with air bronchograms. Which organism is the most common cause of community-acquired lobar pneumonia in this adult?
- A Staphylococcus aureus
- B Streptococcus pneumoniae ✓
- C Klebsiella pneumoniae
- D Mycoplasma pneumoniae
Correct answer: B. Streptococcus pneumoniae
Explanation
Streptococcus pneumoniae is the most common cause of community-acquired lobar pneumonia in adults, presenting with consolidation and air bronchograms. Staphylococcus aureus is more common post-influenza. Klebsiella is associated with upper lobe cavitation in alcoholics. Mycoplasma causes atypical patchy infiltrates, not dense lobar consolidation.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.