Molecular epidemiology of KPC-producing Klebsiella pneumoniae from invasive infections in Italy: increasing diversity with predominance of the ST512 clade II sublineage

J Antimicrob Chemother. 2016 Dec;71(12):3386-3391. doi: 10.1093/jac/dkw337. Epub 2016 Sep 1.


Objectives: The spread of carbapenem-resistant Enterobacteriaceae (CRE) represents one of the most worrisome problems for clinical medicine worldwide. In Italy, the Antibiotic-Resistance-Istituto Superiore di Sanità surveillance network, in collaboration with the Committee for Antimicrobial Agents of the Italian Society of Clinical Microbiologists, promoted a study to investigate the carbapenem-resistance mechanisms, clonal relatedness and capsular typing of a recent collection of carbapenem-resistant Klebsiella pneumoniae (CR-KP).

Methods: A total of 17 laboratories distributed across Italy collected all consecutive non-replicate CR-KP isolated from invasive infections during two different study periods (2011-12 and 2013). Carbapenemase genes were searched for by filter hybridization and confirmed by PCR and sequencing. KPC-producing K. pneumoniae (KPC-KP) were typed by PFGE and MLST. Capsular types were identified by wzi gene typing.

Results: Of the collected K. pneumoniae isolates (n = 461), the overall proportion of CR-KP was 36.2% (n = 167). The majority (97%) of the CR-KP were positive for the blaKPC gene. Among the KPC-KP population, nine different STs were detected with the majority of isolates (94%) belonging to the clonal group (CG) 258. A subpopulation that belonged to ST512 and showed an identical PFGE profile represented the majority (57%) of KPC-KP strains, with a countrywide distribution. Capsular characterization showed the predominance of the wzi154, cps-2 capsular type (88.8% of all CG258 strains). ST258 strains were associated with both cps-1 and cps-2 capsular types, while ST512 was associated with cps-2 only.

Conclusions: Although a trend to a polyclonal evolution of the Italian KPC-KP was noted, this study showed that the KPC-KP population remained largely oligoclonal with the wide diffusion of an ST512 lineage carrying cps-2 capsular type and producing the KPC-3 enzyme.

Publication types

  • Multicenter Study

MeSH terms

  • Cross-Sectional Studies
  • Electrophoresis, Gel, Pulsed-Field
  • Genetic Variation*
  • Genotype*
  • Humans
  • Italy / epidemiology
  • Klebsiella Infections / epidemiology*
  • Klebsiella Infections / microbiology*
  • Klebsiella pneumoniae / classification*
  • Klebsiella pneumoniae / enzymology*
  • Klebsiella pneumoniae / genetics
  • Klebsiella pneumoniae / isolation & purification
  • Molecular Epidemiology
  • Multilocus Sequence Typing
  • Serogroup
  • beta-Lactamases / genetics*


  • beta-Lactamases