2811. Real-World Experience Utilizing Cefiderocol for Serious Multidrug Resistant Gram-Negative Infections

Abstract

Abstract Background Cefiderocol is a novel siderophore cephalosporin that demonstrated in vitro activity against carbapenem-resistant Enterobacterales, Acinetobacter baumannii (AB), Pseudomonas aeruginosa (PA), and Stenotrophomonas maltophilia. Cefiderocol demonstrated promising efficacy in randomized, clinical trials; however, real-world utilization of cefiderocol is not well characterized. Methods This was a retrospective study of adults who received cefiderocol for ≥72h for serious meropenem-resistant Gram negative infections at our institution between 11/2021 and 12/2022. Patients with all sources of infection were considered for inclusion. Clinical failure was defined as all-cause 90d or in-hospital mortality, or the lack of resolution of signs or symptoms of infection. Microbiological failure was defined as positive cultures growing the index pathogen after ≥7d of initiating therapy or ≤60d of completing therapy. Descriptive statistics were used to compare outcomes by the index pathogen. Results Of 55 patients who received cefiderocol, 35 patients were included. The remaining 20 patients were excluded for receiving < 72h of therapy. The most common infections were pneumonia (n = 17, 48.6%), skin and skin structure infections (n = 6, 17.1%), and osteomyelitis (n = 5, 14.3%) wherein PA (n = 17, 48.6%) and AB (n = 14, 40%) were isolated most frequently. The overall 90d and in-hospital mortality rates were 9 (25.7%) and 11 (31.4%) patients, respectively. Clinical failure, assessed in 34 patients, occurred in 10 (29.4%) patients and was similar between pathogens (p = 0.71). Microbiological failure, assessed in 26 patients, occurred more commonly in infections caused by PA (n = 11/12, 91.7%) compared to all other pathogens (n = 3/14, 21.4%; p < 0.01). Notably, most microbiological failures due to PA were in the setting of pneumonia (n = 6/11, 54.5%). Conclusion Real-world experience demonstrated that most patients receiving cefiderocol for serious Gram-negative infections did well; however, microbiological failure among patients with PA infections may be attributed to the difficulty in differentiating true pathogens and colonizers in respiratory infections. Disclosures All Authors: No reported disclosures