KPC-53, a KPC-3 Variant of Clinical Origin Associated with Reduced Susceptibility to Ceftazidime-Avibactam

This study reports on the characterization of a Klebsiella pneumoniae clinical isolate showing high-level resistance to ceftazidime-avibactam associated with the production of KPC-53, a KPC-3 variant exhibiting a Leu167Glu168 duplication in the Omega-loop and a loss of carbapenemase activity. Whole-genome sequencing (WGS) revealed the presence of two copies of blaKPC-53, located on a pKpQIL-like plasmid and on a plasmid prophage of the Siphoviridae family, respectively. The present findings provide new in-sights into the mechanisms of resistance to ceftazidime-avibactam.