First Report of Complete Sequence of a bla(NDM-13)-Harboring Plasmid from an Escherichia coli ST5138 Clinical Isolate

Since the first report of bla(NDM-1), 16 bla(NDM) variants have been identified among Gram-negative bacteria worldwide. Recently, a novel bla(NDM) variant, bla(NDM-13), was identified in the chromosome of an ST101 Escherichia coli isolate from Nepal. Here we first reported plasmid-mediated bla(NDM-13) in a carbapenem-resistant E. coli ST5138 clinical isolate associated with hospital-acquired urinary tract infection from China. bla(NDM-13) and bla(SHV-12) coexisted on the a ~54 Kb self-transferable plasmid. Compared with NDM-1, NDM-13, NDM-3, and NDM-4 had two amino acid substitutions (D95N and M154L), one amino acid substitution (D95N) and one amino acid substitutions (M154L), respectively. Complete plasmid sequencing showed that bla(NDM-13)-harboring plasmid (pNDM13-DC33) was highly similar to the bla(NDM-1)-harboring IncX3 plasmid pNDM-HN380, a common bla(NDM)-harboring vector circulating in China. In accordance with the structure of pNDM-HN380, pNDM13-DC33 consists of a 33-kb backbone encoding plasmid replication (repB), stability partitioning, and transfer (tra, trb, and pil) functions, and a 21-kb antimicrobial resistance region with high GC content between umuD and mpr genes. In conclusion, the present study is the first report of a plasmid-encoded bla(NDM-13) and the complete sequence of a bla(NDM-13)-harboring plasmid (pNDM13-DC33). bla(NDM-13) maybe originate from bla(NDM-1) located on a pNDM-HN380-like plasmid by sequential mutations.