Phylogenomic Investigation of IncI1-Iγ Plasmids Harboring bla CMY-2 and bla SHV-12 in Salmonella enterica and Escherichia coli in Multiple Countries.

The objective of this study was to elucidate the genetic and evolutionary relatedness of bla CMY-2- and bla SHV-12-carrying IncI1-Iγ plasmids. Phylogenomic analysis based on core genome alignments and gene presence/absence was performed for different IncI1-Iγ sequence types (STs). Most IncI1-Iγ/ST12 and IncI1-Iγ/ST231 plasmids had near-identical core genomes. The data suggest that widely occurring bla CMY-2-carrying IncI1-Iγ/ST12 plasmids originate from a common ancestor. In contrast, bla SHV-12 was inserted independently into different IncI1-Iγ/ST231-related plasmids.