Which antibiotic is used as single-dose therapy for uncomplicated UTIs?

• A. Fosfomycin
• B. Nitrofurantoin
• C. TMP-SMX
• D. Ciprofloxacin

Answer: (A)

Single-dose oral therapy for uncomplicated UTIs is possible when the drug achieves high and persistent concentrations in urine to eradicate the typical pathogens with a one-time dose. Fosfomycin trometamol fits this well: a single 3 g dose rapidly concentrates in the urinary tract and inhibits early steps of bacterial cell wall synthesis by targeting MurA, making it effective in a one-off treatment for cystitis caused by common organisms like E. coli.

This is why it’s the best choice among the options. The other agents are normally given for multiple days—nitrofurantoin for about five days, and TMP-SMX or a fluoroquinolone like ciprofloxacin typically for three days—so they don’t meet the single-dose criterion as reliably.