An XDR Pseudomonas aeruginosa ST463 Strain with an IncP-2 Plasmid Containing a Novel Transposon Tn6485f Encoding bla(IMP-45) and bla(AFM-1) and a Second Plasmid with Two Copies of bla(KPC-2)

The increased carbapenem resistance among Pseudomonas aeruginosa has become a serious health issue worldwide. We reported an extensively drug-resistant (XDR) P. aeruginosa PA30 isolate which belonged to sequence type ST463 and contained an IncP-2 plasmid (pPA30_1) carrying two genes, namely, bla(IMP-45) and bla(AFM-1), which encoded the metallo-β-lactamases AFM-1 and IMP-45, respectively. Additionally, the strain had a plasmid (pPA30_2) with two copies of the bla(KPC-2) genes embedded. The plasmid pPA30_1 was highly similar to the previously reported plasmid pHS17-127, which has the same genetic architecture. This plasmid contained bla(IMP-45), located in a second gene cassette of the integron In786, carried by a Tn1403-derivative transposon acquiring an ISCR27n3-bla(AFM-1) structure. Interestingly, the transposon in pPA30_1 acquired an extra ISCR1-qnrVC6 module and formed a novel transposon, which was subsequently annotated as Tn6485f. The bla(KPC-2) genes in pPA30_2 underwent duplication due to the inversion of the IS26-bla(KPC-2)-IS26 element, which resulted in two copies of bla(KPC-2). IMPORTANCE The ST463 clone is an emerging high-risk sequence type that is spreading with bla(KPC-2)-containing plasmids. The core bla(KPC-2) genetic platform is ISKpn27-bla(KPC-2)-ISKpn6 in almost all samples, and the adjacent region beyond the core platform varies by IS26-mediated inversion or duplication events, amplifying the bla(KPC-2) gene copies. The ST463 P. aeruginosa strain PA30 in our study contains another two metallo-β-lactamase genes, namely, bla(IMP-45) and bla(AFM-1), in a novel transposon Tn6485f that is harbored by the IncP-2 megaplasmid. The pPA30_1 carrying bla(IMP-45) and bla(AFM-1) is highly related to pHS17-127 from the ST369 P. aeruginosa strain, indicating the putative dissemination of the megaplasmid between different clones.