Impact of extended-spectrum chromosomal AmpC (ESAC) of on susceptibility to cefiderocol.

Unlabelled: The impact of chromosomally encoded wild-type or extended-spectrum (ESAC) AmpC β-lactamases of on susceptibility to ceftazidime, cefepime, and cefiderocol was evaluated in different genetic backgrounds, including wild-type, PBP3-modified, and porin-deficient strains. Recombinant strains possessing the different backgrounds and producing variable ESACs were evaluated. Although ESAC enzymes conferred resistance to ceftazidime and decreased susceptibility to cefepime as expected, we showed here that cefiderocol was also a substrate of ESAC enzymes.

Importance: We showed here that chromosomally encoded intrinsic extended-spectrum cephalosporinases of may impact susceptibility not only to ceftazidime and cefepime but also to cefiderocol.