Molecular in-depth evaluations of OXA-48 and NDM-1 Co-harboring Klebsiella pneumoniae isolates

Carbapenem-resistant K. pneumoniae has become endemic in Europe, as well as in Italy, where its prevalence has risen dramatically, above all sustained by epidemic clones harboring metallo-enzymes. This study aims to investigate the dissemination of OXA-48 and NDM-1 co-producer K. pneumoniae strains across hospitals in southern Italy using molecular analyses. A total of 49 K. pneumoniae strains, predominantly co-producing OXA-48 and NDM-1, from March to December 2023, were collected. Antibiotic susceptibility testing was conducted following EUCAST guidelines. Whole-genome sequencing (Illumina MiSeq) and bioinformatics tools (CARD, CLC Genomics Workbench) were used to identify resistance and virulence genes, capsule loci, and phylogenetic relationships. All isolates exhibited multidrug-resistant or extensively drug-resistant profiles, including resistance to ceftazidime/avibactam and meropenem/vaborbactam. Genomic analysis revealed diverse resistance genes such as blaOXA-48, blaNDM-1, blaCTX-M-15, and blaSHV variants. Virulence genes associated with capsules, fimbriae, and siderophores were widespread. Most strains were classified as ST147 by MLST, containing various plasmids known to be antimicrobial resistance carriers.Phylogenetic analysis confirmed clonal relatedness, highlighting intra-hospital dissemination of high-risk clones. High-risk K. pneumoniae clones, particularly ST147, pose significant challenges in healthcare settings due to extensive antimicrobial resistance driven by plasmid-borne resistance genes, including co-produced carbapenemases like blaNDM-1 and blaOXA-48. Molecular monitoring of these clones is essential for improving targeted infection control strategies, mitigating the spread of multidrug-resistant pathogens, and managing their clinical impact effectively.