Multiclonal dispersal of KPC genes following the emergence of non-ST258 KPC-producing Klebsiella pneumoniae clones in Madrid, Spain.

OBJECTIVES: To analyse the ongoing epidemiology of KPC-producing Enterobacteriaceae after a non-ST258 KPC-3-producing Klebsiella pneumoniae outbreak in a university hospital in Madrid, Spain.
METHODS: Enterobacterial isolates (one per patient based on bacterial identification and typing patterns) with carbapenem MICs higher than the EUCAST epidemiological cut-off values, a positive modified Hodge test and carbapenem/boronic acid combination disc test results were studied (16 March 2010 to 31 January 2012) and compared with KPC-producing isolates previously described in our institution (September 2009 to February 2010). The bacterial population structure (PFGE and multilocus sequence typing), carbapenemase genes and KPC plasmids were studied. Patients' clinical records were reviewed.
RESULTS: Twenty-four KPC-producing Enterobacteriaceae (20 K. pneumoniae, 2 Escherichia coli and 2 Enterobacter cloacae) from 23 patients (13 males, median age 72 years) were studied. Most KPC-producer strains were considered as colonizers. Six K. pneumoniae clones (ST11, ST20, ST384, ST454, ST659 and ST971), two E. coli clones (ST224 and ST357) and one E. cloacae clone were identified. blaKPC-3 was located on IncFIIK plasmids of ∼100 kb (E. coli ST357 and K. pneumoniae ST384, ST454, ST659 and ST971 clones) and on IncN plasmids of ∼40 kb (K. pneumoniae ST11 clone). Non-typeable plasmids of ∼20 kb containing blaKPC-2 were detected in scarcely represented clones (K. pneumoniae ST20, E. coli ST224 and E. cloacae).
CONCLUSIONS: During the 2 year period following the emergence of non-ST258 KPC-3-producing K. pneumoniae isolates in our institution, the blaKPC-3 and blaKPC-2 genes efficiently penetrated other Enterobacteriaceae lineages. Non-ST258 K. pneumoniae isolates were mostly responsible for the dissemination of KPC enzymes, producing a complex epidemiological picture.