In vitro Activity of Cefiderocol and Comparators against Carbapenem-Resistant Gram-Negative Pathogens from France and Belgium.

Infections with carbapenem-resistant (CR) Gram-negative (GN) pathogens have increased in many countries worldwide, leaving only few therapeutic options. Cefiderocol (CFDC) is approved in Europe for the treatment of aerobic GN infections in adults with limited treatment options. This study evaluated the in vitro activity of cefiderocol and comparators against multidrug-resistant (MDR) bacteria including meropenem-resistant (MR) or pandrug-resistant (PR) GN clinical isolates from France and Belgium. The minimum inhibitory concentrations (MICs) of CFDC were determined by broth microdilution, using iron-depleted cation-adjusted Mueller-Hinton broth, and were compared to those of 10 last-line antibiotics. The MICs were interpreted according to EUCAST and CLSI breakpoints, and in the absence of species-specific breakpoints, non-species-related pharmacokinetic/pharmacodynamic breakpoints were used. Among the 476 isolates tested, 322 were carbapenemase producers (CP), 58 non-CP-CRs, 52 intrinsically CR, 41 expanded-spectrum cephalosporin resistant and 5 were multi-susceptible. Susceptibility to CFDC was high using EUCAST breakpoints 81%, 99% and 84%, and was even higher using CLSI breakpoints to 93%, 100% and 88% for Enterobacterales, Pseudomonas aeruginosa and Acinetobacter baumannii , respectively. Susceptibility to cefiderocol using non-species-related breakpoints for Stenotrophomonas maltophilia , Achromobacter xylosoxydans and Burkholderia cepacia , was 100%, 100% and 92.3%, respectively. The susceptibility rates were lower with the NDM producers, with values of 48% and 30% using EUCAST breakpoints and 81% and 50% using CLSI breakpoints for Enterobacterales and Acinetobacter spp, respectively. CFDC demonstrated high in vitro susceptibility rates against a wide range of MDR GN pathogens, including MR and PR isolates.