Characterization of bla NDM-19 -producing IncX3 plasmid isolated from carbapenem-resistant Escherichia coli and Klebsiella pneumoniae .

The increase in the prevalence of carbapenem-producing Enterobacterales (CPE) is a major threat, with the New Delhi metallo-β-lactamase (NDM) enzyme-producing CPEs being one of the major causative agents of healthcare settings infections. In this study, we characterized an IncX3 plasmid harboring bla NDM-19 in Lebanon, recovered from three Escherichia coli belonging to ST167 and one Klebsiella pneumoniae belonging to ST16 isolated from a clinical setting . Plasmid analysis using PBRT, Plasmid Finder, and PlasmidSPAdes showed that all four isolates carried a conjugative 47-kb plasmid having bla NDM-19, and was designated as pLAU-NDM19. We constructed a sequence-based maximum likelihood phylogenetic tree and compared pLAU-NDM19 to other representative IncX3 plasmids carrying NDM-variants and showed that it was closely linked to NDM-19 positive IncX3 plasmid from K. pneumoniae reported in China. Our findings also revealed the route mediating resistance transmission, the IncX3 dissemination among Enterobacterales, and the NDM-19 genetic environment. We showed that mobile elements contributed to the variability of IncX3 genomic environment and highlighted that clonal dissemination in healthcare settings facilitated the spread of resistance determinants. Antimicrobial stewardship programs implemented in hospitals should be coupled with genomic surveillance to better understand the mechanisms mediating the mobilization of resistance determinants among nosocomial pathogens and their subsequent clonal dissemination.