Molecular characterization of VIM-producing Klebsiella pneumoniae from Scandinavia reveals genetic relatedness with international clonal complexes encoding transferable multidrug resistance.

VIM-producing Klebsiella pneumoniae (VPKP) has been identified as a source of hospital outbreaks and is prevalent particularly in the Mediterranean region. In this study we have characterized eight VPKP isolates identified in Scandinavia during 2005-2008. With the exception of one isolate, all were from patients with recent history of hospitalization abroad (Greece, n = 6; Turkey, n = 1). Multilocus sequence typing (MLST) resulted in five sequence types (STs), ST36 (n = 1), ST147 (n = 4), ST272 (n = 1), ST273 (n = 1) and ST383 (n = 1), which except for ST272 were part of putative international clonal complexes. All were multidrug resistant due to the presence of other resistance determinants, including extended-spectrum β-lactamases (CTX-M-3, SHV-5 and SHV-12), 16S rRNA methylases (ArmA) and plasmid-mediated quinolone resistance determinants (QnrS). One isolate harboured a novel VIM-variant (VIM-26) while VIM-1 and VIM-19 were detected in six and one isolate, respectively. Two different genetic structures surrounding the bla(VIM) gene were identified in four isolates. In two isolates bla(VIM-1) and bla(VIM-26) were located in an integron similar to In-e541 (intI1;bla(VIM-1/-26);aacA7; dhfrI;aadA1;3'CS) while in the other two isolates bla(VIM-1) was located in an integron lacking 3'CS but with an IS26 element in the 3'end (intI1;bla(VIM-1);aac(6')-Ib;IS26), as identified in the IncN plasmid pKOX105. The bla(VIM) -genes were located on transferable plasmids ranging from ∼40 to ∼240 kb and associated with Tn21 in four isolates. PCR-based replicon typing indicated association of bla(VIM) with IncN (n = 3) and A/C (n = 1) broad-host-range plasmids but also with unknown replicons (n = 4). In conclusion, Scandinavian VPKP is associated with importation and genetically related to international clones encoding transferable plasmid-mediated multidrug resistance.