title: Sequence of closely related plasmids encoding bla(NDM-1) in two unrelated Klebsiella pneumoniae isolates in Singapore.
abstract: BACKGROUND
  Spread of the bla(NDM-1) gene that encodes the New Delhi metallo-β-lactamase (NDM-1) in Enterobacteriaceae is a major global health problem. Plasmids carrying bla(NDM-1) from two different multi-drug resistant Klebsiella pneumonia isolates collected in Singapore were completely sequenced and compared to known plasmids carrying bla(NDM-1).
  
  
  RESULTS
  The two plasmids, pTR3 and pTR4, were transferred to Escherichia coli recipient strain J53 and completely sequenced by a shotgun approach using 3-kb paired-end libraries on 454. Although the K. pneumoniae strains were unrelated by molecular typing using PFGE and MLST, complete sequencing revealed that pTR3 and pTR4 are identical. The plasmid sequence is similar to the E. coli NDM-1-encoding plasmid p271A, which was isolated in Australia from a patient returning from Bangladesh. The immediate regions of the bla(NDM-1) gene in pTR3/4 are identical to that of p271A, but the backbone of our plasmid is much more similar to another IncN2 plasmid reported recently, pJIE137, which contained an additional 5.2-kb CUP (conserved upstream repeat) regulon region in comparison to p271A. A 257-bp element bounded by imperfect 39-bp inverted repeats (IR) and an incomplete version of this element flanking the 3.6-kb NDM-1-encoding region were identified in these plasmids and are likely to be the vestiges of an unknown IS.
  
  
  CONCLUSIONS
  Although the hosts are not epidemiologically linked, we found that the plasmids bearing the bla(NDM-1) gene are identical. Comparative analyses of the conserved NDM-1-encoding region among different plasmids from K. pneumoniae and E. coli suggested that the transposable elements and the two unknown IR-associated elements flanking the NDM-1-encoding region might have aided the spreading of this worrisome resistance determinant.
authors.affiliation: Institute of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan, Taiwan.
authors.forename: Ying-Tsong
authors.initials: YT
authors.lastname: Chen
authors.forename: Ann-Chi
authors.initials: AC
authors.lastname: Lin
authors.forename: L Kristopher
authors.initials: LK
authors.lastname: Siu
authors.forename: Tse Hsien
authors.initials: TH
authors.lastname: Koh
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001483:Base Sequence; D003227:Conjugation, Genetic / Q000187:drug effects; D006801:Humans; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology* / Q000302:isolation & purification*; D008297:Male; D008826:Microbial Sensitivity Tests; D058977:Molecular Sequence Annotation; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics*; D012846:Singapore; D055815:Young Adult; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D001618:beta-Lactamases; C552864:beta-lactamase NDM-1