Which fluoroquinolone demonstrates the best activity against Streptococcus pneumoniae and atypical pathogens, making it suitable for community-acquired pneumonia monotherapy?

• A Ciprofloxacin
• B Norfloxacin
• C Nalidixic acid
• D Levofloxacin ✓

Explanation

Levofloxacin (and moxifloxacin) are respiratory fluoroquinolones with enhanced gram-positive activity, particularly against S. pneumoniae, Legionella, Mycoplasma, and Chlamydophila. Their improved pneumococcal coverage stems from greater inhibition of topoisomerase IV (the primary target in gram-positives) relative to ciprofloxacin. Ciprofloxacin has poor pneumococcal activity; norfloxacin and nalidixic acid are restricted to UTIs and lack systemic tissue penetration.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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