Genomic Features and Virulence Characteristics of a Community-Acquired Bloodstream Infection-Causing HypervirulentKlebsiella pneumoniaeST86 Strain Harboring KPC-2-Encoding IncX6 Plasmid

The emergence and spread of carbapenem-resistant hypervirulentKlebsiella pneumoniae(CR-hvKP) is causing worldwide concern. Sequence type (ST) 86K. pneumoniae, a major hvKP clone, is rarely resistant to carbapenem. In this study, we report the genomic features and virulence characteristics of a community-acquired bloodstream infection (CA-BSI)-causing CR-hvKP ST86 strain (KPN55602). This strain is resistant to carbapenem but sensitive to amikacin, gentamicin, tigecycline, and colistin. According toin vitroandin vivovirulence assessments, it was classified as hypervirulent. Whole-genome sequencing revealed that KPN55602 has a single 5.13 Mb chromosome and two plasmids. The chromosome of KPN55602 is phylogenetically similar to those of other sequenced ST86 strains. The incompatibility (Inc) group HI1B plasmid pK55602_1, harboring a set of virulence genes, was classified as a virulence plasmid. The IncX6 plasmid pK55602_2, carryingbla(KPC-2), was transferable through conjugation and is highly homologous to all five sequencedbla(KPC)-bearing IncX6 plasmids. In conclusion, to our knowledge, this is the first report of a CA-BSI-causing CR-hvKP ST86 strain harboring an exogenousbla(KPC-2)-bearing IncX6 plasmid, supplementing existing knowledge on the CR-hvKP evolutionary scenario. The IncX6 plasmid may be an important vehicle forbla(KPC), and its horizontal transfer may have led to CR-hvKP evolution in the community setting.

Automated summary

The study revealed the genomic features and virulence characteristics of a community-acquired bloodstream infection (CA-BSI)-causing carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) ST86 strain. The strain is resistant to carbapenem but sensitive to other antibiotics and classified as hypervirulent based on virulence assessments. The discovery sheds light on the evolution of CR-hvKP and the potential role of IncX6 plasmid in its horizontal transfer.