Complete Nucleotide Sequence of a Novel Plasmid Bearing the High-Level Tigecycline Resistance Gene tet (X4)

We reported the complete nucleotide sequence of a (X4)-carrying plasmid, pSTB20-1T, from a tigecycline-resistant isolate in China. Sequence analysis indicated that pSTB20-1T contains a hybrid plasmid backbone and a (X4)-containing multidrug resistance region, likely originated through recombination of multiple plasmids. (X4) was flanked by two IS , which may be responsible for (X4) mobilization. The occurrence and transmission of this novel hybrid plasmid may exacerbate the spread of the clinically significant (X4) gene.