A 28-year-old man with severe community-acquired pneumonia requires ICU admission. Empiric therapy with ceftriaxone and azithromycin is initiated. Azithromycin provides coverage against atypical pathogens. Which organism among the following is NOT adequately covered by azithromycin monotherapy?
- A Mycoplasma pneumoniae
- B Legionella pneumophila ✓
- C Chlamydophila pneumoniae
- D Ureaplasma urealyticum
Correct answer: B. Legionella pneumophila
Explanation
Azithromycin has good activity against Mycoplasma, Chlamydophila, and Ureaplasma. However, Legionella pneumophila pneumonia requires higher doses or fluoroquinolones for reliable monotherapy; macrolides work but levofloxacin/moxifloxacin are preferred for severe Legionella. This question tests knowledge of macrolide spectrum limitations in severe pneumonia.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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