부산대학교 도서관

ABSTRACTblaNDMgenes confer carbapenem resistance and have been identified on transferable plasmids belonging to different incompatibility (Inc) groups. Here we present the complete sequences of four plasmids carrying a blaNDMgene, pKP1-NDM-1, pEC2-NDM-3, pECL3-NDM-1, and pEC4-NDM-6, from four clinical samples originating from four different patients. Different plasmids carry segments that align to different parts of the blaNDMregion found on Acinetobacterplasmids. pKP1-NDM-1 and pEC2-NDM-3, from Klebsiella pneumoniaeand Escherichia coli, respectively, were identified as type 1 IncA/C2plasmids with almost identical backbones. Different regions carrying blaNDMare inserted in different locations in the antibiotic resistance island known as ARI-A, and ISCR1may have been involved in the acquisition of blaNDM-3by pEC2-NDM-3. pECL3-NDM-1 and pEC4-NDM-6, from Enterobacter cloacaeand E. coli, respectively, have similar IncFIIYbackbones, but different regions carrying blaNDMare found in different locations. Tn3-derived inverted-repeat transposable elements (TIME) appear to have been involved in the acquisition of blaNDM-6by pEC4-NDM-6 and the rmtC16S rRNA methylase gene by IncFIIYplasmids. Characterization of these plasmids further demonstrates that even very closely related plasmids may have acquired blaNDMgenes by different mechanisms. These findings also illustrate the complex relationships between antimicrobial resistance genes, transposable elements, and plasmids and provide insights into the possible routes for transmission of blaNDMgenes among species of the Enterobacteriaceaefamily.