Moxifloxacin is preferred over ciprofloxacin for community-acquired pneumonia due to atypical organisms because it:
- A Preferentially inhibits DNA gyrase with greater potency against Gram-positive and atypical pathogens ✓
- B Has a longer half-life enabling once-weekly dosing
- C Does not inhibit CYP3A4, reducing drug interactions in elderly patients
- D Penetrates the blood-brain barrier more effectively than ciprofloxacin
Correct answer: A. Preferentially inhibits DNA gyrase with greater potency against Gram-positive and atypical pathogens
Explanation
Moxifloxacin is a respiratory fluoroquinolone with enhanced activity against Gram-positive cocci (Streptococcus pneumoniae) and atypical organisms (Mycoplasma, Chlamydophila, Legionella) due to its C8-methoxy substitution, which increases potency against both DNA gyrase (Gram-negative target) and topoisomerase IV (Gram-positive target). Ciprofloxacin has excellent Gram-negative coverage but poor Gram-positive/atypical activity, making it unsuitable as monotherapy for CAP.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.