title: Pathogenicity of pan-drug-resistant Serratia marcescens harbouring blaNDM-1.
abstract: OBJECTIVE
  To characterize a pan-drug-resistant Serratia marcescens clinical isolate carrying the New Delhi metallo-β-lactamase (NDM)-1.
  
  
  METHODS
  The presence of β-lactamase genes was examined by PCR and sequencing. Antibiotic susceptibility was determined by antibiotic gradient test. Transformation assays, transconjugation assays, PFGE and PCR-based replicon typing were used for plasmid analysis. Horizontal gene transfer was evaluated by liquid mating using Escherichia coli J53 as a recipient. Pathogenicity of NDM-1 expressing S. marcescens was analysed using the Galleria mellonella infection model.
  
  
  RESULTS
  S. marcescens isolate SM1890 was non-susceptible to all tested antibiotics, with minocycline retaining intermediate activity. blaNDM-1 was located on a 140 kb IncA/C-type plasmid which was transferable to E. coli and Klebsiella pneumoniae by conjugation. The LD50 of the NDM-positive, SM1890 isolate was higher than that of other, NDM-1 negative, S. marcescens strains.
  
  
  CONCLUSIONS
  The presence of a blaNDM-1-harbouring IncA/C plasmid resulted in marked resistance to β-lactam antibiotics, but had no significant effect on virulence of isogenic strains. Because of the intrinsic resistance of S. marcescens to colistin and reduced susceptibility to tigecycline, treatment options for infections by NDM-1-positive isolates are extremely limited in this species.
authors.affiliation: Institute of Medical Microbiology and Infection Control, Hospital of Johann Wolfgang Goethe-University, Frankfurt am Main, Germany.
authors.forename: Teresa M
authors.initials: TM
authors.lastname: Gruber
authors.affiliation: Institute of Medical Microbiology and Infection Control, Hospital of Johann Wolfgang Goethe-University, Frankfurt am Main, Germany stephan.goettig@kgu.de.
authors.forename: Stephan
authors.initials: S
authors.lastname: Göttig
authors.affiliation: Institute of Medical Microbiology and Infection Control, Hospital of Johann Wolfgang Goethe-University, Frankfurt am Main, Germany.
authors.forename: Laura
authors.initials: L
authors.lastname: Mark
authors.affiliation: Institute of Medical Microbiology and Infection Control, Hospital of Johann Wolfgang Goethe-University, Frankfurt am Main, Germany.
authors.forename: Sara
authors.initials: S
authors.lastname: Christ
authors.affiliation: Institute of Medical Microbiology and Infection Control, Hospital of Johann Wolfgang Goethe-University, Frankfurt am Main, Germany.
authors.forename: Volkhard A J
authors.initials: VA
authors.lastname: Kempf
authors.affiliation: Institute of Medical Microbiology and Infection Control, Hospital of Johann Wolfgang Goethe-University, Frankfurt am Main, Germany.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Wichelhaus
authors.affiliation: Institute of Medical Microbiology, Immunology and Hygiene, University Hospital of Cologne, Cologne, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Hamprecht
mesh_terms: D000818:Animals; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004195:Disease Models, Animal; D024901:Drug Resistance, Multiple, Bacterial; D006801:Humans; D007915:Lepidoptera; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010957:Plasmids / Q000032:analysis; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D016868:Serratia Infections / Q000382:microbiology* / Q000473:pathology; D012706:Serratia marcescens / Q000187:drug effects / Q000201:enzymology* / Q000302:isolation & purification / Q000472:pathogenicity*; D014774:Virulence; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D001618:beta-Lactamases; C552864:beta-lactamase NDM-1
keywords: Enterobacteriaceae; Galleria mellonella; IncA/C; carbapenemases