Intravenous Fosfomycin for Difficult-to-Treat Infections: A Real-Life Multicentric Study in Italy

• Published in: Antibiotics (Basel) Vol. 14; no. 4; p. 401
• Main Authors: Zerbato, Verena, Sanson, Gianfranco, Fusaro, Lisa, Gerussi, Valentina, Sincovich, Sara, Dellai, Fabiana, Del Fabro, Giovanni, Geremia, Nicholas, Maurel, Cristina, Giacomazzi, Donatella, Biasinutto, Chiara, Di Girolamo, Filippo Giorgio, Scrivo, Gianfranco, Costantino, Venera, Di Santolo, Manuela, Busetti, Marina, Crocè, Lory Saveria, Giuliano, Simone, Crapis, Massimo, Zhanel, George, Tascini, Carlo, Luzzati, Roberto, Di Bella, Stefano
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 14.04.2025; MDPI
• Subjects: Amides; Antibiotics; Bacteria; Bacterial pneumonia; Biofilms; Care and treatment; Clinical medicine; difficult-to-treat infections; Drug resistance; E coli; Endocarditis; Enzymes; Fosfomycin; Gram-negative bacteria; Gram-positive bacteria; Health aspects; Infectious diseases; Intravenous administration; intravenous fosfomycin; Lungs; Methicillin; Microorganisms; Molecular weight; multidrug resistance; Pathogens; Patients; Penicillin G; Piperacillin; Pneumonia; Staphylococcus infections; Tazobactam; Urinary tract; Urinary tract infections; Urogenital system; β Lactamase; β-Lactam antibiotics; Italy; difficult-to-treat infections; multidrug resistance; intravenous fosfomycin
• ISSN: 2079-6382; 2079-6382
• DOI: 10.3390/antibiotics14040401

Background: Fosfomycin, an old antibiotic attracting renewed interest, offers a broad spectrum of activity and unique synergy with other agents. While widely used in severe infections, real-world data on intravenous fosfomycin remain limited. Objectives: This study aimed to describe the clinical and microbiological characteristics of patients treated with intravenous fosfomycin and to analyze its administration modalities in a real-world setting. Methods: A multicenter retrospective cohort study was conducted across five Italian hospitals. Adult patients receiving intravenous fosfomycin between January 2020 and December 2023 were included. Results: We enrolled 393 patients. The median age was 69 years, with most patients (45%) admitted to Critical Care Units. Pneumonia (34%), bloodstream infections (22%), and urinary tract infections (21%) were the most common indications. Gram-negative bacteria, particularly E. coli and P. aeruginosa, were the predominant pathogens. Fosfomycin was used as empirical therapy in 55% of cases and was combined with other agents in almost all cases (99%). The most frequent partners were piperacillin/tazobactam (21%) and new beta-lactam/beta-lactamase inhibitor combinations (18%). The median treatment duration was seven days, with most subjects (65%) receiving a fosfomycin dosage regimen of 16 g/day. Minimum inhibitory concentrations (MICs) values for fosfomycin were available for 61 isolates (15%), with 78.7% (48/61) showing MIC ≤ 32 mg/L. C. difficile infection occurred in only 2% of patients. Mortality rates at 30, 60, and 90 days were 21.6%, 26.7%, and 29.3%, respectively. Conclusions: This study provides valuable insights into the real-world use of intravenous fosfomycin.