Characterization of an IncFII Plasmid Encoding NDM-1 from Escherichia coli ST131

Background The current spread of the gene encoding the metallo-ß-lactamase NDM-1 in Enterobacteriaceae is linked to a variety of surrounding genetic structures and plasmid scaffolds. Methodology The whole sequence of plasmid pGUE-NDM carrying the bla NDM-1 gene was determined by high-density pyrosequencing and a genomic comparative analysis with other bla NDM-1 -negative IncFII was performed. Principal Findings Plasmid pGUE-NDM replicating in Escherichia coli confers resistance to many antibiotic molecules including β-lactams, aminoglycosides, trimethoprim, and sulfonamides. It is 87,022 bp in-size and carries the two β-lactamase genes bla NDM-1 and bla OXA-1 , together with three aminoglycoside resistance genes aacA4 , aadA2 , and aacC2 . Comparative analysis of the multidrug resistance locus contained a module encompassing the bla NDM-1 gene that is actually conserved among different structures identified in other enterobacterial isolates. This module was constituted by the bla NDM-1 gene, a fragment of insertion sequence IS Aba125 and a bleomycin resistance encoding gene. Significance This is the first characterized bla NDM-1 -carrying IncFII-type plasmid. Such association between the bla NDM-1 gene and an IncFII-type plasmid backbone is extremely worrisome considering that this plasmid type is known to spread efficiently, as examplified with the worldwide dissemination of bla CTX-M-15 -borne IncFII plasmids.