Antimicrobial resistance, virulence defects, and evolutionary dynamics of multidrug-resistant Klebsiella pneumoniae from human and animal hosts in Central China.

UNLABELLED: The global dissemination of multidrug-resistant Klebsiella pneumoniae (MDR-KP) poses a critical One Health challenge. This study investigated the antimicrobial resistance (AMR) profiles, virulence determinants, and zoonotic transmission risks of K. pneumoniae isolates from humans (n = 10) and animals (n = 42), including bovine, porcine, and avian sources (ducks), in Central China. Whole-genome sequencing and phenotypic assays revealed a high prevalence of multidrug resistance (MDR) (92.3%, 48/52) among K. pneumoniae isolates, with host-specific resistance rates: 100% in isolates from bovine and ducks, 90.9% in porcine isolates, and 70% in human isolates. Phylogenetic analysis revealed clustering of animal-derived sequence types (ST35, ST101, and ST592) with human clinical isolates, indicating potential cross-species transmission. No convergence of high virulence and MDR was observed. A representative ST11-KL64 strain (KP-HB21H30845) exhibited low virulence despite harboring canonical virulence gene clusters (iuc, rmpA, and iroN). Genetic characterization identified a 45-bp deletion within the rmpA promoter region, located within an ISKpn26-formed composite transposon on plasmid pKP845_1, which likely disrupts gene expression. Adjacent to iroN genes positioned near ISKpn26 insertion sites may face transcriptional interference, contributing to attenuated virulence phenotypes. The plasmid-borne existence of AMR determinants (blaKPC-2 and blaCTX-M-65) and virulence loci (iuc and ybt on ICEKp) highlights the emerging risk of MDR hypervirulent K. pneumoniae (MDR-hvKP). These findings underscore the urgent need for integrated surveillance and antimicrobial stewardship across human-animal interfaces to mitigate MDR-KP dissemination in both veterinary and clinical environments.

IMPORTANCE

MDR K. pneumoniae strains (ST35, ST101, and ST592) from animal hosts show genomic linkage to clinical human isolates, signaling interspecies transmission risks. The attenuated virulence of the ST11-KL64 is attributed to ISKpn26-mediated suppression of rmpA expression, a key regulator of hypervirulence in K. pneumoniae.