Fosfomycin tromethamine achieves single-dose oral treatment of uncomplicated cystitis. Its antibacterial action results from inhibition of which bacterial target?
- A Undecaprenyl pyrophosphate carrier lipid recycling
- B Transpeptidation reaction catalyzed by penicillin-binding proteins
- C MurA enolpyruvyl transferase, blocking the first committed step of peptidoglycan synthesis ✓
- D D-alanine:D-alanine ligase involved in precursor synthesis
Correct answer: C. MurA enolpyruvyl transferase, blocking the first committed step of peptidoglycan synthesis
Explanation
Fosfomycin is a phosphonic acid analogue that covalently inactivates MurA, the enolpyruvyl transferase catalyzing the condensation of UDP-N-acetylglucosamine with phosphoenolpyruvate, the first committed cytoplasmic step of peptidoglycan synthesis. It enters cells via glycerophosphate and glucose-6-phosphate transporters. Inhibition of PBPs defines beta-lactams and vancomycin blocks the D-Ala-D-Ala terminus, making options B and D incorrect.
Reference: Katzung Basic and Clinical Pharmacology, 16th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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