We report 2 independent patients from whom carbapenem and ceftazidime-avibactam-resistant Enterobacter cloacae complex strains were identified. The ceftazidime-avibactam resistance was attributed to a 2-amino acid deletion in the R2 loop of AmpC β-lactamase, which concurrently caused resistance to cefepime and reduced susceptibility to cefiderocol, a novel siderophore cephalosporin.
Keywords: R2 loop; cefepime; deletion; β-lactamase.
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