A Plasmid Carrying blaIMP-56 in Pseudomonas aeruginosa Belonging to a Novel Resistance Plasmid Family.

blaIMP and blaVIM are the most detected plasmid-encoded carbapenemase genes in Pseudomonas aeruginosa. Previous studies have reported plasmid sequences carrying blaIMP variants, except blaIMP-56. In this study, we aimed to characterize a plasmid carrying blaIMP-56 in a P. aeruginosa strain isolated from a Mexican hospital. The whole genome of P. aeruginosa strain PE52 was sequenced using Illumina Miseq 2 × 150 bp, with 5 million paired-end reads. We characterized a 27 kb plasmid (pPE52IMP) that carried blaIMP-56. The phylogenetic analysis of RepA in pPE52IMP and 33 P. aeruginosa plasmids carrying resistance genes reported in the GenBank revealed that pPE52IMP and four plasmids (pMATVIM-7, unnamed (FDAARGOS_570), pD5170990, and pMRVIM0713) were in the same clade. These closely related plasmids belonged to the MOBP11 subfamily and had similar backbones. Another plasmid (p4130-KPC) had a similar backbone to pPE52IMP; however, its RepA was truncated. In these plasmids, the resistance genes blaKPC-2, blaVIM variants, aac(6')-Ib4, blaOXA variants, and blaIMP-56 were inserted between phd and resolvase genes. This study describes a new family of plasmids carrying resistance genes, with a similar backbone, the same RepA, and belonging to the MOBP11 subfamily in P. aeruginosa. In addition, our characterized plasmid harboring blaIMP-56 (pPE52IMP) belongs to this family.