A 22-year-old student presents with dry cough, low-grade fever and bilateral patchy infiltrates. Cold agglutinins are positive and Mycoplasma pneumoniae serology returns positive. Which antibiotic class provides first-line oral coverage for this organism along with Legionella and Chlamydophila species?

• A Aminoglycosides
• B Metronidazole
• C First-generation cephalosporins
• D Macrolides ✓

Explanation

The atypical respiratory pathogens, namely Mycoplasma pneumoniae, Legionella pneumophila and Chlamydophila pneumoniae, lack a peptidoglycan cell wall or reside intracellularly, making them invisible to beta-lactams. Macrolides inhibit protein synthesis on the 50S ribosome, penetrate cells well, and are standard first-line therapy for these organisms. Aminoglycosides require aerobic active uptake and are ineffective against intracellular pathogens, while metronidazole has no activity against these organisms.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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