Molecular Epidemiology of Hypervirulent Carbapenemase-Producing Klebsiella pneumoniae

OBJECTIVE: To investigate the overall distributions of key virulence genes in Klebsiella pneumoniae, especially the hypervirulent bla (KPC)-positive K. pneumoniae (Hv-bla (KPC)(+)-KP). METHODS: A total of 521 complete genomes of K. pneumoniae from GenBank were collected and analyzed. Multilocus sequence typing, molecular serotyping, antibiotic-resistance, virulence genes and plasmid replicon typing were investigated. RESULTS: Positive rates of virulence genes highly varied, ranging from 2.9 (c-rmpA/A2) to 99.6% (entB). Totally 207 strains presented positive fimH, mrkD, entB and wzi and 190 showed positive fimH, mrkD, entB, irp2 and wzi, which were the two primary modes. A total of 94, 165 and 29 strains were denoted as hypervirulent K. pneumoniae (HvKP), bla (KPC)(+)-KP and Hv-bla (KPC)(+)-KP. ST11 accounted for 17 among the 29 Hv-bla (KPC)(+)-KP strains; Genes iucA, p-rmpA2 and p-rmpA were positive in 28, 26 and 18 Hv-bla (KPC)(+)-KP strains respectively. Among the 29 Hv-bla (KPC)(+)-KP strains exhibiting four super clusters from GenBank, IncHI1B plasmids carrying virulence genes and IncFII ones with bla (KPC) were responsible for both 23 strains respectively. CONCLUSIONS: Positive rates of virulence genes vary remarkably in K. pneumoniae. Genes iucA, p-rmpA2 and p-rmpA were primary ones inducing Hv-bla (KPC)(+)-KP. IncHI1B plasmids carrying virulence genes and IncFII ones with bla (KPC) constitute the primary combination responsible for Hv-bla (KPC)(+)-KP. The making of Hv-bla (KPC)(+)-KP is mostly via bla (KPC)(+)-KP acquiring another plasmid harboring virulence genes.