Limited Evidence of Spillover of Antimicrobial-Resistant Klebsiella pneumoniae from Animal/Environmental Reservoirs to Humans in Vellore, India

Background: Klebsiella pneumoniae is a common opportunistic pathogen in humans, often associated with both virulence and antimicrobial resistance (AMR) phenotypes. K. pneumoniae have a highly plastic genome and can act as a vehicle for disseminating genetic information. Aiming to assess the impact of the human-animal-environment interface on AMR dissemination in K. pneumoniae we sampled and genome sequenced organisms from a range of environments and compared their genetic composition.

Methods: Representative K. pneumoniae isolated from clinical specimens (n = 59), livestock samples (n = 71), and hospital sewage samples (n = 16) during a two-year surveillance study were subjected to whole genome sequencing. We compared the taxonomic and genomic distribution of K. pneumoniae, AMR gene abundance, virulence gene composition, and mobile genetic elements between the three sources.

Results: The K. pneumoniae isolates originating from livestock were clonally distinct from those derived from clinical/hospital effluent samples. Notably, the clinical and hospital sewage isolates typically possessed a greater number of resistance/virulence genes than those from animals. Overall, we observed a limited overlap of K. pneumoniae clones, AMR genes, virulence determinants, and plasmids between the different settings.

Conclusion: In this setting, the spread of XDR and hypervirulent clones of K. pneumoniae appears to be restricted to humans with no obvious association with non-clinical sources. Emergent clones of K. pneumoniae carrying both resistance and virulence determinants are likely to have emerged in hospital settings rather than in animal or natural environments. These data challenge the current view of AMR transmission in K. pneumoniae in a One-Health context.