Genomic Features and Virulence Characteristics of a Community-Acquired Bloodstream Infection-Causing Hypervirulent Klebsiella pneumoniae ST86 Strain Harboring KPC-2-Encoding IncX6 Plasmid.

The emergence and spread of carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) is causing worldwide concern. Sequence type (ST) 86 K. 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 to in vitro and in vivo virulence 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, carrying blaKPC-2, was transferable through conjugation and is highly homologous to all five sequenced blaKPC-bearing IncX6 plasmids. In conclusion, to our knowledge, this is the first report of a CA-BSI-causing CR-hvKP ST86 strain harboring an exogenous blaKPC-2-bearing IncX6 plasmid, supplementing existing knowledge on the CR-hvKP evolutionary scenario. The IncX6 plasmid may be an important vehicle for blaKPC, and its horizontal transfer may have led to CR-hvKP evolution in the community setting.