Characterization of a Novel IncHI2 Plasmid Carrying Tandem Copies of bla CTX-M-2 in a fosA6 -Harboring Escherichia coli Sequence Type 410 Strain

The extended-spectrum β-lactamase gene bla CTX-M-2 is mainly associated with IS CR1 embedded in complex sul1 -type integrons, but information on the genetic context of plasmids harboring the IS CR1-bla CTX-M-2 module remains limited. In this study, a bla CTX-M-2 -harboring plasmid (pYD786-1) belonging to the sequence type 2 (ST2)-IncHI2 plasmid type and isolated from an Escherichia coli ST410 clinical strain was sequenced and analyzed. pYD786-1 belongs to the APEC-O1-R-type IncHI2 plasmids, which are widely distributed in human, poultry, and livestock strains. It contains a multidrug resistance mosaic region (MRR) consisting of a Tn 21 ::In2 transposon backbone augmented by acquisition of duplicate IS CR1-bla CTX-M-2 modules. Tn 2411 , a Tn 21 ::In2 precursor, likely played a role in the generation of the MRR in pN13-01290_23, the putative progenitor plasmid of pYD786-1, found in a foodborne Salmonella strain. Tn 21/ Tn 2411 ::In::IS CR1-bla CTX-M-2 derivatives, including pYD786-1, have been identified in strains from Europe, South America, and the United States, suggesting potential global dissemination of the bla CTX-M-2 modules mediated by this vehicle.