Safety and Efficacy Study of Oral Fosfomycin Versus Oral Levofloxacin to Treat Complicated Urinary Syndromes (FOCUS)

This is a Phase 4, multi-center, open-label, randomized pragmatic superiority clinical trial comparing two strategies for initial or step-down oral therapy for complicated urinary tract infections (cUTI) without bacteremia with a uropathogen after 0-48 hours of parenteral antibiotic therapy. The trial will evaluate the success and safety of a strategy of initial or step-down fosfomycin, administered at a dose of 3 g once daily, vs. a strategy of initial or step-down levofloxacin administered at a dose of 750 mg once daily. Investigator-directed adjustment to another adequate oral therapy is allowed 1) if the causative pathogen is not susceptible in vitro to quinolone initial or step-down therapy in a subject randomized to the levofloxacin strategy, OR 2) if the subject develops an intolerance or allergy to the initial step-down oral therapy and at the investigator's discretion, OR 3) the subject has an underlying condition posing increasing risk for adverse events from quinolone therapy. The duration of oral therapy (initial + subsequent if indicated) in each strategy is 5-7 days of any per protocol antibiotic to which the pathogen is susceptible. The dosing of oral therapy depends on creatinine clearance (CrCl). The trial will enroll approximately 634 patients that are either male or female aged 18 or older with cUTI from outpatient and inpatient settings. The study will take place over 25 months in up to 15 US sites. The primary objective is to compare Strategy 1 and Strategy 2 in terms of treatment success rates at Test of Cure (TOC). The secondary objectives are: 1) to assess the safety of Fosfomycin; 2) to compare Strategy 1 and Strategy 2 in terms of solicited adverse events; 3) to compare Strategy 1 and Strategy 2 in terms of treatment success rates at End of Therapy (EOT).