This study investigated a strain of Klebsiella pneumoniae, identified as GRTHES, which exhibited extensive antibiotic resistance. The strain was resistant to all beta-lactams, including combinations with newer agents such as meropenem/vaborbactam and imipenem/relebactam, as well as to aminoglycosides, fluoroquinolones, fosfomycin, trimethoprim-sulfamethoxazole and colistin. It remained susceptible to tigecycline. Whole-genome sequencing was performed by Ion Torrent platform on the K. pneumoniae strain. Genomic analysis revealed a genome length of 5,808,650 bp and a GC content of 56.9%. Advanced sequencing techniques and bioinformatic tools were used to assess resistance genes and plasmid replicons, highlighting the emergence of multidrug resistance and virulence traits. The strain carried blaNDM-1 and blaKPC-3 genes and was designated to KL107 O2afg type. Colistin resistance-associated mgrB/pmrB gene mutations were present, and the strain also harbored yersiniabactinencoding ybt gene. Our findings provide insights into the genomic context of blaNDM-1 and blaKPC-3 carbapenemase-producing K. pneumoniae and emphasize the importance of continuous surveillance and novel therapeutic strategies to combat multidrug-resistant bacterial infections. It is the first time that an NDM-1 and KPC-3 co-producing strain of K. pneumoniae ST512 is identified in Greece. This study highlights the essential role of genomic surveillance as a proactive strategy to control the spread of carbapenemase-producing K. pneumoniae isolates, particularly when key antimicrobial resistance genes, such as blaNDM-1 and blaKPC-3, are plasmid-mediated. Detailed characterization of these isolates could reveal plasmid similarities that facilitate adaptation and transmission within and between hospitals. Although data on patient movements are limited, it is plausible that carbapenemresistant isolate was selected to co-produce KPC and NDM through plasmid acquisition.  Kulcsszavak: carbapenemase, antimicrobial resistance, whole-genome sequencing