5PSQ-082 Use, efficacy and safety of cefiderocol in infections caused by multidrug-resistant gram-negative microorganisms

<h3>Background and Importance</h3> Cefiderocol, a siderophore cephalosporin, shows remarkable activity against multidrug-resistant gram-negative bacteria (MR-GNB). Its use is restricted to cases where no other therapeutic options are available. <h3>Aim and Objectives</h3> To analyse the use, efficacy and safety of cefiderocol in patients admitted with MR-GNB infections. <h3>Material and Methods</h3> Observational and retrospective study including patients treated with cefiderocol for at least 3 days, between January 2021 and August 2024. The following variables were recorded: age, sex, causative microorganism and mechanism of resistance, indication, duration of treatment, antibiogram and comorbidities. The outcome variables analysed were microbiological eradication (negative culture after completion of treatment or absence of symptoms) and 28-day mortality. Safety was assessed as treatment discontinuation due to adverse effects. <h3>Results</h3> Thirty-six patients treated with cefiderocol were analysed; 93.5% (33) were male and median age 64 (28–90) years. 26 were infected with carbapenemase B-producing <i>Pseudomonas</i> (20 IMP, 7 VIM, 2 NDM), four <i>Acinetobacter baumanii</i>, two non-carbapenemase-producing <i>Pseudomonas aeruginosa</i>, two carbapenemase B-producing enterobacteria (NDM), one <i>Stenotrophomonas</i> and one extended-spectrum beta-lactamase-producing <i>Escherichia coli</i>. The main infections were pneumonias 44% (16) (12 associated with mechanical ventilation), followed by urinary tract infections 30% (11) and bacteraemias 11% (4). The remaining 15% were minor infections (one intra-abdominal infection, 1 peritonitis, two pressure ulcers, one colonisation). The mean duration of treatment was 11 (SD 4.8) days, achieving microbiological eradication in 75% (27). Mortality before 28 days was 16.67% (6). In terms of safety, two patients discontinued treatment due to adverse reactions (myoclonus and rash). <h3>Conclusion and Relevance</h3> The data obtained reveal favourable results in terms of microbiological eradication and mortality reduction, which positions this treatment as a highly effective option for infections caused by MR-GNB, especially in cases where therapeutic alternatives are limited. It also has a good safety profile, as adverse reactions were mild and disappeared when treatment was discontinued. It should be noted that some patients had multiple pathologies and comorbidities, and in these cases cefiderocol was used at an advanced stage of treatment. <h3>References and/or Acknowledgements</h3> <h3>Conflict of Interest</h3> No conflict of interest