Clinical effectiveness and bacteriological eradication of three different Short-COurse antibiotic regimens and single-dose fosfomycin for uncomplicated lower Urinary Tract infections in adult women (SCOUT study): study protocol for a randomised clinical trial.

Introduction: Uncomplicated lower urinary tract infections (uLUTI) are a common problem in primary care. Current local guidelines recommend the use of a single 3 g dose of fosfomycin. However, most general practitioners (GP) prefer short-course therapies to single-dose therapy. No study has compared head-to-head short-course antimicrobial agents for uLUTIs. Therefore, the aim of this randomised clinical trial is to compare three different short-course antibiotic therapies with a single-dose of fosfomycin for these infections.

Methods And Analysis: This will be a pragmatic, multicentre, parallel group, open trial. Women aged 18 or older and with symptoms of uLUTI and a positive urine dipstick analysis will be randomised to one of the following four groups: a single dose of 3 g of fosfomycin, 2 days of 3 g of fosfomycin o.d., 3 days of pivmecillinam 400 mg three times per day (t.i.d) or 5 days of nitrofurantoin 100 mg t.i.d. A total sample of 1120 patients was calculated. The primary endpoint is clinical effectiveness at day 7, defined as cure of symptoms reported by the patients in a diary including four symptoms: dysuria, urgency, frequency and suprapubic pain, which will be scored on a 4-point severity scale (not present/mild/moderate/severe). Follow-up visits are scheduled at days 7 (phone call), 14 and 28 for assessing evolution. Urine samples will be collected in the three on-site visits and urine cultures performed. If positive, antibiograms for the three antibiotics studied will be performed. Bacterial eradication will be measured at days 14 and 28.

Ethics And Dissemination: The study was approved by the Ethical Board of IDIAP Jordi Gol (reference number: 21/173-AC) and Spanish Agency of Medicines and Medical Devices. The findings of this trial will be disseminated through research conferences and peer-review journals.

Trial Registration Number: NCT04959331; EudraCT Number: 2021-001332-26.

Time Schedule: January 2022 to April 2023.