Ceftolozane/Tazobactam Versus Meropenem for Febrile Neutropenia on Patients Colonized With or at Risk for Infection With Extended Spectrum Beta Lactamase - Producing Pathogens

The study proposes a planned, double-blind, non-inferiority clinical trial involving patients with febrile neutropenia and risk of extended-spectrum beta-lactamase (ESBL) infection. The goal is: \- Analyze the efficacy and tolerability of Ceftolozane/tazobactam (CEF/TAZ) compared to the current standard of care (meropenem) in patients with febrile neutropenia and risk of ESBL infection. Patients will be randomly assigned to receive CEF/TAZ or meropenem, with assessment of clinical response, toxicity and microbiological evolution. Stool samples will be collected before, during and after treatment for intestinal microbiota analysis and intestinal microbiome analysis to evaluate possible effects on GVHD. Analysis of the results will include the taxonomic classification of the organisms present. Data will be analyzed to assess non-inferiority in clinical response, incidence of GVHD, antimicrobial resistance and other outcomes.