Activity of Cefiderocol Against Carbapenem-Resistant and .

The objective of this study was to assess the susceptibility of cefiderocol against multidrug-resistant carbapenemase-producing and nonproducing bacteria. The panel comprised 182 isolates of the order , and 40 strains of . Antimicrobial susceptibility testing has been performed using broth microdilution method according to the European Committee on Antimicrobial Susceptibility Testing recommendations. Mass spectrometry matrix-assisted laser desorption/ionization-time of flight mass spectrometry and carbapenemase-producing test were used to verify the presence of carbapenemases in clinical isolates. The genetic expression of single carbapenemases (, , , , , ) was determined by real-time polymerase chain reaction. Cefiderocol exhibited a good activity against the majority of strains tested in this study. Altogether, growth of 81.9% ( = 149) strains of the order and 77.5% ( = 31) of isolates were inhibited at minimal inhibitory concentration (MIC) ≤2 mg/L. Values MIC/MIC were 0.5/8 mg/L for enterobacteria, and 1/8 mg/L for . One isolate () harboring two carbapenemases (, ) had cefiderocol MIC 0.5 mg/L. In enterobacteria resistant to cefiderocol, carbapenemase prevailed (43.3%,  = 29), followed by (31.3%,  = 21) and (4.5%,  = 3). ( = 8) and a ( = 1) metallo-β-lactamases dominated in cefiderocol-resistant ( = 9) isolates. Very good susceptibility (100%) to this drug showed -positive strains of ( = 8) and isolates resistant to meropenem without confirmed carbapenemase gene ( = 10). In this study, cefiderocol demonstrated potent activity against important nosocomial pathogens, therefore, therapeutic options of this drug against multidrug-resistant bacteria should be considered.