A Combination Therapy With Ceftazidime and Fosfomycin Will be Compared to Ceftazidime Alone in Hospitalized Adult Patients With Suspected Severe Gram-negative Bacterial Infections

"The intervention will last 72h (±6h). Ceftazidime will be administered intravenously in 5% glucose serum (per hospital standard), either intermittently (divided into three doses daily) or as continuous infusion; doses will be adapted to renal function. The decision to administer CAZ by continuous infusion and to add AVI will be left to the attending physician. CAZ±AVI will be adjusted for renal insufficiency per internal guidelines of dosing and international recommendations.~The use of CAZ with its paired beta-lactamase inhibitor avibactam, i.e., the use of ceftazidime-avibactam (Zavicefta®) instead of CAZ will occur in case of suspicion of infection by either extended-spectrum-beta-lactamase-producing Enterobacterales (ESBL-E), cephalosporinase-carrying Enterobacterales (ampC-E) or carbapenem-resistant Enterobacterales (CRE), as determined by treating physician and/or the infectious diseases consultant."

Participants randomized to the control arm will receive placebo infusion. Placebo will be 5% glucose serum and will be administered IV with the same frequency as FOS would be for the participant's renal function.