title: Transfer of an Escherichia coli ST131 multiresistance cassette has created a Klebsiella pneumoniae-specific plasmid associated with a major nosocomial outbreak.
abstract: OBJECTIVE
  To characterize the complete sequence, horizontal spread and stability of the CTX-M-15-encoding multiresistance plasmid of a Klebsiella pneumoniae strain involved in a large nosocomial outbreak.
  
  
  METHODS
  The 220 kbp plasmid pUUH239.2 was completely sequenced using 454 technology. The conjugational host range, conjugation frequencies, plasmid stability and fitness cost of plasmid carriage were studied in vitro. Conjugational spread during the outbreak was assessed retrospectively by multiplex PCR screening, restriction fragment length polymorphism and PFGE.
  
  
  RESULTS
  Plasmid pUUH239.2 encodes resistance to β-lactams (bla(CTX-M-15), bla(TEM-1) and bla(OXA-1)), aminoglycosides [aac-(6')-1b-cr and aadA2], tetracyclines [tet(A) and tetR], trimethoprim (dhfrXII), sulphonamides (sul1), quaternary ammonium compounds (qacEΔ1), macrolides [mph(A)-mxr-mphR(A)] and heavy metal ions (silver, copper and arsenic). The plasmid consists of a backbone, highly similar to the K. pneumoniae plasmid pKPN3, and a 41 kbp resistance region, highly similar to the resistance regions of plasmids pEK499 and pC15-1a previously isolated from Escherichia coli strains belonging to the outbreak lineage ST131 (where ST stands for sequence type). The pUUH239.2 plasmid is stable in K. pneumoniae but unstable in E. coli and confers a fitness cost when introduced into a naive host cell. Transfer of pUUH239.2 from the outbreak K. pneumoniae clone to the E. coli of the patients' intestinal floras has occurred on multiple occasions during the outbreak.
  
  
  CONCLUSIONS
  The plasmid pUUH239.2 is a composite of the pKPN3 K. pneumoniae plasmid backbone and the bla(CTX-M-15)-encoding multiresistance cassette associated with the internationally recognized outbreak strain E. coli ST131. The resulting plasmid differs in stability between K. pneumoniae and E. coli, and this has probably limited the spread of this plasmid during the outbreak.
authors: Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden. linus.sandegren@imbim.uu.se
authors: Linus
authors: L
authors: Sandegren
authors: Marius
authors: M
authors: Linkevicius
authors: Birgitta
authors: B
authors: Lytsy
authors: Åsa
authors: Å
authors: Melhus
authors: Dan I
authors: DI
authors: Andersson
mesh_terms: D003227:Conjugation, Genetic; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004196:Disease Outbreaks; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000235:genetics; D022761:Gene Transfer, Horizontal; D058507:Host Specificity; D006801:Humans; D007710:Klebsiella Infections / Q000453:epidemiology* / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D008969:Molecular Sequence Data; D058889:Molecular Typing; D060885:Multiplex Polymerase Chain Reaction; D010957:Plasmids; D012150:Polymorphism, Restriction Fragment Length; D017422:Sequence Analysis, DNA; D001618:beta-Lactamases / Q000235:genetics
chemical_list: D004269:DNA, Bacterial; C473109:beta-lactamase CTX-M-15; D001618:beta-Lactamases