Genotypic and Phenotypic Characterization of Clinical Escherichia coli Sequence Type 405 Carrying IncN2 Plasmid Harboring blaNDM-1

We report a bla(NDM)-carrying ST405 Escherichia coli recovered from the abdominal fluid of a patient in Shandong, China. This strain belonged to the high-risk phylogenetic group D and carried the virulence genes, papG II, papG III, papC, and iroN. In addition to bla(NDM-1), this isolate carried the quinolone resistance gene acc(6')-Ib and extended-spectrum beta-lactamase (ESBL) genes bla(CTX-M-)(15) and bla(CTX-M-)(14). bla(NDM-1) was located on a 41 Kb IncN2 self-transmissible plasmid. The IncN2 plasmid named as pJN24NDM1 was fully sequenced and analyzed. Genome comparative analysis showed that IncN2 plasmids harboring carbapenem-resistance genes possessed conserved backbones and variable accessory regions. Phylogenetic analysis of 87 IncN plasmids based on orthologous genes indicated that 9 IncN2 plasmids fell into one phylogenetic Glade, while 4 IncN3 plasmids were in two phylogenetic clades of the 74 IncN1 plasmids. The presence of IncN2 plasmids harboring bla(NDM) in the high-risk clone ST405 E. coli raises serious concerns for its potential of dissemination.