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

• Published in: Journal of antimicrobial chemotherapy Vol. 71; no. 12; pp. 3386 - 3391
• Main Authors: Conte, Viola, Monaco, Monica, Giani, Tommaso, D'Ancona, Fortunato, Moro, Maria Luisa, Arena, Fabio, D'Andrea, Marco Maria, Rossolini, Gian Maria, Pantosti, Annalisa
• Format: Journal Article
• Language: English
• Published: England 01-12-2016
• Subjects: beta-Lactamases - genetics; 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
• ISSN: 0305-7453; 1460-2091
• DOI: 10.1093/jac/dkw337

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).
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.
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 bla
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.
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.