PO Antibiotics for UTI

Drug Mechanism Dosing (5 days)
Nitrofurantoin monohydrate/ macrocrystals (Macrobid) reactive intermediates inactivate/alter bacterial ribosomal proteins 100mg BID x 5 days (women) 7d for men
Trimethoprim-sulfamethoxazole (Bactrim) interferes with purine and therefore DNA synthesis DS tablet (160/800 mg) twice daily for 3 days
Fosfomycin inhibits synthesis of peptidoglycan by blocking formation of N-acetylmuramic acid 3 g as a single dose
Pivmecillinam binds and inactivates penicillin-binding protein 2 (PBP 2) 400 mg orally twice daily for 5-7 days
Levaquin inhibits bacterial topoisomerase IV and DNA gyrase (uUTI) 250mg for 3 days
(cUTI) 750 mg for 5 days
Ciprofloxacin 250 mg every 12 hours for 3 days
Cephalexin binds and inactivates PBPs 500mg BID for 5-7 days

uUTI = uncomplicated UTI, cUTI=complicated UTI 

Lower UTI in pregnancy:

  • Nitrofurantoin (Macrobid): 100 mg PO b.i.d. × 7 days (5)
  • Cephalexin (Keflex): 500 mg PO b.i.d. × 7 days

UTI during pregnancy always requires culture/sensitivity and usually requires a 7–14-day treatment.