Klebsiella pneumoniae is now recognized as an urgent threat to human health due to the emergence of multi-drug resistant strains associated with hospital outbreaks, however this is overlaid against a background of constant, antimicrobial resistant, hospital-acquired infections probably stemming from human carriage. We have recently completed a large-scale genomic survey incorporating K. pneumoniae from carriage and infection in humans and animals on four continents. The analysis provides a comprehensive genetic framework for K. pneumoniae, revealing a highly diverse species with a large accessory genome, including genes conferring resistance to all classes of antimicrobials used to treat Gram-negative bacterial infections. Antimicrobial resistance genes were most common amongst human carriage isolates and hospital-acquired infections, and these two populations were genomically indistinguishable. I will also present data from a recent hospital study conducted in Australia, investigating the frequency of commensal K. pneumoniae carriage in the community and its role in hospital acquired infections.