With the aim of demonstrate the clinical non-inferiority of intravenous fosfomycin compared to meropenem or ceftriaxone in the treatment of bacteraemic urinary tract infections caused by multidrug-resistant Escherichia coli . The investigators propose a "real practise" randomised, controlled, multicentre phase III clinical trial to compare the clinical and microbiological efficacy and safety of intravenous fosfomycin (4 grammes every 6 hours) with meropenem (1 gramme every 8 hours) or ceftriaxone (1 gramme every 24 hours) as targeted therapy of the previously specified infection; change to oral therapy according to predefined options is allowed in both arms after 5 days. Follow-up for the study is planned up to 60 days.