A 26-year-old pregnant woman at 14 weeks has uncomplicated cystitis caused by nitrofurantoin-resistant E. coli. She reports a history of anaphylaxis to penicillin. Which agent, given as a single oral dose, is appropriate and acts by inhibiting enolpyruvyl transferase (MurA) in the first step of peptidoglycan synthesis?
- A Levofloxacin 750 mg
- B Nitrofurantoin macrocrystals
- C Fosfomycin tromethamine ✓
- D Amoxicillin-clavulanate
Correct answer: C. Fosfomycin tromethamine
Explanation
Fosfomycin, a phosphoenolpyruvate analogue, irreversibly inhibits MurA, the enzyme catalyzing the first committed step of peptidoglycan synthesis, and is given as a single 3 g oral dose for uncomplicated cystitis. It is safe in pregnancy and useful when organisms are resistant to first-line agents. Nitrofurantoin was excluded by the resistance profile, fluoroquinolones are avoided in pregnancy, and amoxicillin-clavulanate requires multiple doses and is contraindicated by the penicillin anaphylaxis history.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.