Molecular characterization of a clinical ST145 <i>Klebsiella oxytoca</i> strain co-producing KPC-2 and IMP-96 carbapenemases

Carbapenem-resistant <i>Klebsiella oxytoca</i> has been increasingly reported worldwide; however, isolates co-producing both class A and class B carbapenemases remain rare. This study reported a clinical ST145 <i>K. oxytoca</i> isolate co-harboring the <i>bla</i>_KPC-2 and <i>bla</i>_IMP-96 resistance genes, which exhibited high-level resistance to both carbapenems and ceftazidime-avibactam. The two carbapenemase genes were located on conjugative plasmids separately with autonomous transfer capability. Genetic context analysis revealed that both resistance genes were embedded in mobile genetic elements, which likely mediate their capture and horizontal transfer across bacterial species. The widespread distribution of such mobile elements carrying resistance genes accelerates the evolution of multidrug-resistant bacteria. Genomic analysis of global ST145 <i>K. oxytoca</i> strains further indicated that this sequence type represents a high-risk, multidrug-resistant clonal lineage with significant public health implications. Enhanced surveillance and screening of ST145 <i>K. oxytoca</i> are warranted to limit its further global spread.