Fosfomycin tromethamine, given as a single oral dose for uncomplicated lower urinary tract infection, acts by:

• A Inhibiting DNA gyrase in uropathogens
• B Chelating membrane magnesium ions and disrupting the outer membrane
• C Binding the 23S rRNA component of the 50S ribosomal subunit
• D Irreversibly inhibiting enolpyruvyl transferase (MurA), blocking early peptidoglycan synthesis ✓

Explanation

Fosfomycin is a phosphonic acid analogue of phosphoenolpyruvate that irreversibly inhibits MurA (UDP-N-acetylglucosamine enolpyruvyl transferase), the first committed cytoplasmic step of peptidoglycan synthesis. Its structural class and target differ completely from beta-lactams, so it shows no cross-resistance with them. Single-dose therapy works because it achieves high urinary concentrations for prolonged periods.

Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.