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 blaVIM gene were identified in four isolates. In two isolates blaVIM-1 and blaVIM-26 were located in an integron similar to In-e541 (intI1;blaVIM-1/-26;aacA7; dhfrI;aadA1;3’CS) while in the other two isolates blaVIM-1 was located in an integron lacking 3’CS but with an IS26 element in the 3’end (intI1;blaVIM-1;aac(6’)-Ib;IS26), as identified in the IncN plasmid pKOX105. The blaVIM-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 blaVIM 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.