164. in Vitro Antibacterial Activity of Cefiderocol Against Non-fermenter Clinical Strains Collected in North America and Europe from Multinational Surveillance Studies SIDERO-WT-2014–2018

Abstract

Session: O-32. Novel agents Background: The efficacy and safety of cefiderocol (CFDC), a novel siderophore cephalosporin, for the treatment of serious infections due to carbapenem-resistant (CR) Gram-negative pathogens was assessed in the CREDIBLE-CR study. The current analysis evaluated clinical and microbiological outcomes by baseline CR pathogen. Methods: An open-label, prospective, randomised 2:1, Phase 3 study (CREDIBLE-CR; NCT02714595) was conducted in adult patients with hospital-acquired , ventilator-associated, and healthcare-associated pneumonia, bloodstream infections or sepsis, and complicated urinary tract infections caused by CR Gram-negative pathogens. Patients received either intravenous (IV) CFDC 2g, q8h, 3-h infusion, or IV best available therapy (BAT: up to 3 drugs in combination), for 7-14 days (extendable to 21 days). Clinical and microbiological outcomes were assessed in the CR microbiological intent-to-treat (CR-MITT) population by CR pathogen, baseline MIC and by mechanism of carbapenem resistance at test of cure (TOC). Only summary statistics were collected. Results: In the CR-MITT population (CFDC N=80; BAT N=38), Acinetobacter baumannii (46.3% and 44.7%), Klebsiella pneumoniae (33.8% and 31.5%), and Pseudomonas aeruginosa (15% and 26%) were the most frequent pathogens in CFDC and BAT arms, respectively. For all CR pathogens, clinical cure rates were achieved in 52.5% in the CFDC arm and 50.0% in the BAT arm at TOC; rates were similar between treatment arms by baseline CR pathogen (Table 1). Numerically higher clinical cure and microbiological outcomes were observed with CFDC for Enterobacterales (Table 1), especially against NDM-producing bacteria or those with porin-channel mutations (Table 1). CFDC MIC values ranged between ≤0.03 and 4 μg/mL, except for one pathogen (Table 2). Microbiological outcomes for CR A. baumannii, CR K. pneu-moniae, and CR P. aeruginosa at TOC by baseline MICs of ≤4 μg/mL ranged between 0-40%, 0-100%, and 0-100%, respectively; at MIC ≤4 μg/mL, clinical and microbio-logical outcomes were equal (Table 2).