OXA-1207, a new OXA-48-type carbapenem-hydrolysing class D beta lactamase from Escherichia coli

1.We present the characterisation of OXA-1207, a novel, plasmid-encoded OXA-48-like carbapenemase identified in two unrelated Escherichia coli (sequence type (ST) ST405 and ST4405) isolates from hospital patients in Germany. OXA-1207 is closely related to OXA-181, differing by two amino acid substitutions (214G and 244W). The blaOXA-1207 gene was located on a self-transmissible IncFIC plasmids (pOXA-1207) featuring a conserved backbone and the novel {Delta}Tn6361 transposon structure, which derived from IncX3 plasmids carrying blaOXA-181. Notably, pOXA-1207 exhibited an exceptionally high conjugation frequency (mean 1.2 x 10-1) to E. coli, surpassing the typical rates reported for widely distributed OXA-48 plasmids. Analysis of public genomic datasets identified 40 E. coli isolates carrying blaOXA-1207, belonging to diverse high-risk clonal lineages (ST167, ST405 and ST410). The isolates originated from multiple continents, indicating global dissemination. These findings highlight OXA-1207 as an emerging and concerning resistance determinant with enhanced transmissibility and emphasise the need for continued molecular surveillance of OXA-48-like carbapenemases.