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.