SP23-3 Characterization of NDM-1

Abstract

indicated that the strain NDM-1-Saitama belonged to sequence type ST42 which had not been reported previously. Complete sequencing and gap closing by PCR demonstrated a 49,441bp IncFII plasmid which bears 53 genes. The plasmid pNDM-1Saitama consists of 22kb backbone and 27kb multi-drug resistant region. Half of the backbone showed 100% perfect match of the sequence ofK. pneumoniae plasmid pKP048which contains blaKPC-2. The second half of the backbone has only partial similarity to the plasmids with blaNDM-1 and blaCTX-M3. The multi-drug resistant region of pNDM-1-Saitama contains 13 drug resistant elements including blaNDM-1, bleMBL, blaDHA-1, sul1, armA, mel, and mph2. The complete sequence of an ISAba125 insertion sequence in the upstream of the blaNDM-1 gene suggests horizontal transfer of the blaNDM-1 gene between Enterobacteriaceae and Acinetobacter . The possible recombination events between NDM-1 plasmids and plasmids carrying KPC and CTXM-3 or A. baumannii genome are suggested. The blaNDM-1 gene is always followed by the bleomycin resistant protein gene bleMBL. The blaNDM-1bleMBL elements are followed either by blaDHA-1 and ampR or molecular chaperones groES and groER. Our study suggests community-acquired blaNDM-1 plasmid has undergone frequent recombination with plasmids carrying other clinically important resistance genes KPC and CTX-M-3.