Identification of Novel Plasmids Containing the Tigecycline Resistance Gene tet(X4) in Escherichia coli Isolated from Retail Chicken Meat

In 2019, transferable plasmid-borne tet(X3)/tet(X4) genes conferring high-level tigecycline resistance were identified in Enterobacteriaceae and Acinetobacter. These transferable tet(X) variants are associated with different plasmids and could further spread and disseminate through associated mobile plasmids, raising public concern. In this study, we report the identification and characterization of two novel plasmids carrying tet(X4) in Escherichia coli isolated from retail chicken meat. We believe that our study contributes to our understanding of the genetic environment of tet(X4) and their transferability and capability of recombination and integration with other resistance genes in plasmids.