Plasmid-mediated convergence of multidrug resistance and hypervirulence in community-acquired Klebsiella pneumoniae in Tianjin, China.

BACKGROUND

Klebsiella pneumoniae is a major bacterial pathogen responsible for community- and hospital-acquired infections. Although strains associated with hospital-acquired disease have been well described, the genomic and phenotypic characteristics of community-acquired K. pneumoniae among community-acquired isolates from this setting remain insufficiently understood. This study aimed to characterize the molecular features, antimicrobial resistance patterns, and virulence-associated traits of community-acquired strains isolated from a tertiary hospital in Tianjin.

RESULTS

A total of 27 community-acquired K. pneumoniae underwent whole-genome sequencing and comprehensive phenotypic assessment. Molecular typing revealed that the dominant lineages included ST11-KL64-O1/O2v1, ST268-KL20-O1/O2v1, and ST15-KL102-O1/O2v2. All isolates carried at least one virulence-associated gene as defined by established hvKp markers and produced high levels of siderophores (> 30 µg/mL). Most strains displayed multidrug-resistant phenotypes and simultaneously possessed virulence determinants, indicating the frequent detection of multidrug-resistant hypervirulent K. pneumoniae among the studied community-acquired isolates. Genomic analysis showed that the coexistence of resistance and virulence traits was largely associated with horizontal gene transfer mediated by mobile genetic elements such as plasmids, insertion sequences, and transposons. Replicons of the IncHI1B and IncFIB plasmid families were frequently linked to virulence-associated genes. Functional assays, including Galleria mellonella infection, biofilm formation, macrophage infection, and serum resistance testing, confirmed the pathogenic potential of these strains. Integrated genomic and phenotypic findings suggested that multiple virulence factors collectively enhance pathogenicity through immune evasion, increased biofilm production, and modulation of host responses.

CONCLUSIONS

Community-acquired K. pneumoniae strains analyzed in this study exhibit a concerning combination of multidrug resistance and enhanced virulence. The convergence of these traits, largely associated with mobile genetic elements, represents an emerging public health concern and underscores the need for strengthened surveillance and targeted control measures.