Novel plasmid-mediated tet (X5) gene conferring resistance to tigecycline, eravacycline and omadacycline in clinical Acinetobacter baumannii .

A novel, plasmid-mediated, high-level tigecycline resistance tet(X) gene variant, tet(X5), was detected in a clinical Acinetobacter baumannii isolate from China in 2017. Tet(X5) shows 84.5% and 90.5% amino acid identity to Tet(X3) and Tet(X4), respectively, with similar binding sites and a comparable affinity for tetracyclines. The tet(X5)-containing plasmid could only be transferred to A. baumannii via electro-transformation. This report follows the recent study describing the identification of tet(X3) and tet(X4).