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, and , 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 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 , located in a second gene cassette of the integron In, carried by a Tn-derivative transposon acquiring an IS- structure. Interestingly, the transposon in pPA30_1 acquired an extra IS- module and formed a novel transposon, which was subsequently annotated as Tn. The genes in pPA30_2 underwent duplication due to the inversion of the IS--IS element, which resulted in two copies of . The ST463 clone is an emerging high-risk sequence type that is spreading with -containing plasmids. The core genetic platform is IS-b-IS in almost all samples, and the adjacent region beyond the core platform varies by IS-mediated inversion or duplication events, amplifying the gene copies. The ST463 P. aeruginosa strain PA30 in our study contains another two metallo-β-lactamase genes, namely, and , in a novel transposon Tn that is harbored by the IncP-2 megaplasmid. The pPA30_1 carrying and is highly related to pHS17-127 from the ST369 P. aeruginosa strain, indicating the putative dissemination of the megaplasmid between different clones.