Emerging Klebsiella pneumoniae co-harboring carbapenemase genes and hypervirulence determinants in Iran: a molecular and phenotypic investigation.

BACKGROUND: Klebsiella pneumoniae is a significant nosocomial pathogen of global concern. The escalating prevalence of multidrug-resistant (MDR) strains, particularly those resistant to carbapenems, poses considerable challenges in clinical management. This study aimed to elucidate the molecular epidemiology of carbapenem resistance and hypervirulence in clinical K. pneumoniae isolates from Iran. METHODS: We investigated the prevalence of carbapenemase genes blaNDM, blaVIM, and blaIMP, and virulence-associated genes magA, rmpA, and K2A, in 41 genetically confirmed clinical isolates collected during 2024–2025. The expression level of rmpA was quantified using quantitative real-time polymerase chain reaction (qRT-PCR). Phenotypic screening for carbapenemase production was performed, and molecular characterization was conducted via PCR. The study was reviewed and approved by the Ethics Committee of Tarbiat Modares University (IR.MODARES.REC.1403.172). RESULTS: Phenotypic screening identified 90.2% of the isolates as carbapenemase producers, classified as serine-type carbapenemase producers (64.9%) and metallo-β-lactamase (MBL) producers (35.1%). PCR confirmed the presence of the targeted resistance and virulence genes, with amplification products matching the expected sizes. Quantitative analysis revealed significantly elevated rmpA gene expression in hypervirulent rmpA+/K2A+ isolates compared to non-hypervirulent isolates (lacking both rmpA and K2A). CONCLUSIONS: These findings underscore the simultaneous presence of antimicrobial resistance and virulence factors in clinical K. pneumoniae populations in Iran. The convergence of these traits suggests a growing public health concern and highlights the potential value of enhanced molecular surveillance. This study provides vital epidemiological data to support efforts aimed at managing complex K. pneumoniae infections and mitigating the risks associated with emerging multidrug-resistant hypervirulent strains.