Introduction: Prolonged use of antibiotics is closely related to antibiotic-associated infections, anti-microbial resistance and adverse drug events. The optimal duration of antibiotic treatment for Gram-negative bacteremia (GNB) with a urinary tract source of infection is poorly defined.

Methods and analysis: Investigator initiated multicenter, non-blinded, non-inferiority randomized controlled trial with two parallel treatment arms. One arm will receive shortened antibiotic treatment of 5 days and the other arm will receive standard antibiotic treatment of 7 days or longer. Randomization will occur in equal proportion (1:1) no later than day 5 of efficacious antibiotic treatment as determined by antibiogram. Immunosuppressed patients and those with GNB due to non-fermenting bacilli (Acinetobacter spp, Pseudomonas spp), Brucella spp, Fusobacterium spp or polymicrobial growth are ineligible.

Primary endpoint is 90-day survival without clinical or microbiological failure to treatment. Secondary endpoints include all-cause mortality, total duration of antibiotic treatment, hospital re-admission and Clostridioides difficile infection. Interim safety analysis will be performed after the recruitment of every 100 patients. Given an event rate of 12%, a margin of 10% and 90% power, the required sample size to determine non-inferiority is 380 patients. Analyses will be performed on both intention-to-treat and per-protocol populations.

Ethics and dissemination: Approval by Ethics Committee and National Competent Authorities will be obtained before initiation of the trial. Results of the main trial and each of the secondary endpoints will be submitted for publication in a peer-reviewed journal.

Impact: Demonstration of non-inferiority will provide needed evidence to safely shorten antibiotic treatment duration in GNB with a urinary tract source of infection and thereby reduce the risk of adverse events and development of resistance associated with use of antibiotics