An XDR Pseudomonas aeruginosa ST463 Strain with an IncP-2 Plasmid Containing a Novel Transposon Tn 6485f 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 In 786 , carried by a Tn 1403 -derivative transposon acquiring an IS CR27n3 - bla AFM-1 structure. Interestingly, the transposon in pPA30_1 acquired an extra IS CR1 - qnrVC6 module and formed a novel transposon, which was subsequently annotated as Tn 6485f . The bla KPC-2 genes in pPA30_2 underwent duplication due to the inversion of the IS 26 - bla KPC-2 -IS 26 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 IS Kpn27 -b la KPC-2 -IS Kpn6 in almost all samples, and the adjacent region beyond the core platform varies by IS 26 -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 Tn 6485f 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.