Complete Sequence of a Novel 178-Kilobase Plasmid CarryingblaNDM-1in a Providencia stuartii Strain Isolated in Afghanistan

Abstract

ABSTRACTIn response to global concerns over the spread of the New Delhi metallo-β-lactamase gene 1,blaNDM-1, a monthly surveillance program was initiated in September 2010. All carbapenem-resistant Gram-negative strains forwarded to our facility are screened for this gene. To date, 321 carbapenem-resistant isolates, encompassing 11 bacterial species, have been tested. In February 2011, two strains ofProvidencia stuartii, submitted from a military hospital in Afghanistan, tested positive forblaNDM-1. Both strains were identical by pulsed-field gel electrophoresis (PFGE).blaNDM-1was carried on a large plasmid, pMR0211, which was sequenced by emulsion PCR and pyrosequencing. pMR0211 is 178,277 bp in size and belongs to incompatibility group A/C. The plasmid consists of a backbone with considerable homology to pAR060302 fromEscherichia coli, and it retains many of the antibiotic resistance genes associated with it. The plasmid also shares common elements with the pNDM-HK plasmid, includingblaNDM-1,armA, andsul1. However, gene orientation is reversed, and a 3-kb fragment from this region is absent from pMR0211. pMR0211 also contains additional genes, including the aminoglycoside-modifying enzyme lociaadAandaac(6′), the quinolone resistance geneqnrA, a gene with highest homology to a U32 family peptidase fromShewanella amazonensis, and theblaOXA-10gene. The finding of this gene in an intrinsically colistin-resistant species such asProvidencia stuartiiis especially worrisome, as it renders the organism resistant to nearly every available antibiotic. The presence of multiple insertion sequences and transposons flanking the region containing theblaNDM-1gene further highlights the potential mobility associated with this gene.