Characterization of multiple NDM-1-producing Enterobacteriaceae isolates from the same patient

Abstract

A male patient was admitted to a community hospital in Ontario, Canada, with an infected sacral ulcer after returning from India, where he was hospitalized. Carbapenem-resistant Escherichia coli (isolated from blood cultures), Enterobacter cloacae, and Providencia stuartii (from urine samples), all positive for bla(NDM-1), were recovered. Comparative NDM-1 plasmid analysis suggests both lateral plasmid transfer and independent acquisition of the bla(NDM-1) gene in these clinical isolates.

FIG 1

Comparison of the NDM plasmids characterized in this study with closely related IncA/C plasmid pNDM-KN (GenBank accession no. JN157804) (9). (A) Regions with high homology are shaded light blue. Arrows indicate the following predicted ORFs: conjugation, stability, and accessory genes (green, yellow), antimicrobial resistance genes (red, bla_NDM-1 is light green), transposon-related genes (blue), and hypothetical proteins (white). The replicase gene is pink. The orange-boxed segments are detailed in panel B. (B) Detail of the bla_NDM-1-flanking regions (those of pNDM-PstGN576 are the same as those of pNDM-EcoGN568). The orange circles represent the 256-bp direct repeats with similarities to MITEs identified in bla_NDM-1 and insA. A third MITE was found ∼11 kb upstream of the bla_NDM-1 gene, between a truncated copy of IS5 and a putative endonuclease III gene.