Shifting molecular epidemiology of carbapenem-resistant Klebsiella pneumoniae in a regional Greek hospital: Department-specific trends and national context (2022-2024).

Carbapenem-resistant Klebsiella pneumoniae (CRKP) poses a growing threat in Greek hospitals, with increasing reports of multidrug- and pandrug-resistant strains; however, molecular data from regional centers remain limited. This study aimed to investigate the molecular epidemiology, resistance mechanisms, and transmission dynamics of CRKP isolates collected at the General Hospital of Volos, Central Greece, between 2022 and 2024. Thirty-seven non-duplicate CRKP isolates were analyzed. Identification and antibiotic susceptibility testing were performed using VITEK® 2, disk diffusion, Etest®, and broth microdilution. Carbapenemase production was assessed using the NG-Test® Carba-5. Eight isolates underwent multilocus sequence typing (MLST). All isolates were resistant to carbapenems, cephalosporins, and fluoroquinolones; furthermore, 40% were colistin-resistant. The dominant carbapenemase genes were blaNDM-1 (45.9%), blaKPC-2 (18.9%), and blaVIM-1 (27.0%), with co-expression of multiple carbapenemases in 30% of the isolates. MLST revealed the high-risk clones ST11, ST15, and ST323, and three intra-intensive care unit (ICU) transmission clusters. The emergence of dual-carbapenemase and colistin-resistant clones underscores the need for local genomic surveillance, improved infection control, and access to newer antimicrobials in non-tertiary settings.