title: [Fitness costs of blaNDM-1 bearing plasmid pNDM-BJ01 in Acinetobacter lwoffii].
abstract: OBJECTIVE
  To investigate the fitness costs of the New Delhi Metallo-beta-lactamase-1 (bIaNDM-1) bearing plasmid pNDM-BJ01 in Acinetobacter lwoffii strain 10621, and to evaluate the potentials of the sustainahility and expansions among the Acinetobacter lwoffii population.
  
  
  METHODS
  We obtained the spontaneous mutant of A. lwoffii missing pNDM-BJ01 10621NDM-1(-) via serial passages of the wild strain 10621NDM1(-) on the antibiotics-free media. We then compared the in vitro fitness of these two strains by measuring the growth curves, the ability of biofilm formation and the survival rates in nutrient-free PBS buffer.
  
  
  RESULTS
  Plasmid pNDM-BJ01 was unstable in A. lwoffii strain 10621, and 11 passages will be enough to get it deleted from the ancestral strain. We found no significant difference in the growth curves either at 26 or 37 degrees C for 10621NDM-1(+) and 10621NDM-1(-). The biofilm formation ability of the plasmid free derivate 10621NDM-1(-) was significant higher than its resistant ancestor 10621NDM-1(+) at 26 degrees C, whereas the latter showed higher ability of biofilm formation at 37 degrees C. Strain 10621NDM-1(+) was vulnerable in the nutrient-free PBS buffer, with less than 5% survival rate on the first day and dying out on the sixth day, whereas 10621NDM-1(-) survived till the seventh day.
  
  
  CONCLUSIONS
  blaNDM-1 bearing plasmid pNDM-BJ01 possesses significant fitness costs in A. lwoffii strain 10621, and it will get depleted easily if the antibiotic press released. pNDM-BJ01-free 10621NDM-1(-) strain has higher fitness than its ancestor, 10621NDM-1(+), which implies the limited expansion potential of plasmid pNDM-BJ01 in A. lwoffii.
authors.affiliation: The Second Hospital of Hebei Medical University, Hebei Provincial Center for Clinical Laboratories, Shijiazhuang 050000, China. xuli0404d@163.com
authors.forename: Li
authors.initials: L
authors.lastname: Xu
authors.forename: Ruichen
authors.initials: R
authors.lastname: Lv
authors.forename: Haiyan
authors.initials: H
authors.lastname: Wang
authors.forename: Hongyan
authors.initials: H
authors.lastname: Hu
authors.forename: Xiangna
authors.initials: X
authors.lastname: Zhao
authors.forename: Ruifu
authors.initials: R
authors.lastname: Yang
authors.forename: Jianhong
authors.initials: J
authors.lastname: Zhao
authors.forename: Yajun
authors.initials: Y
authors.lastname: Song
mesh_terms: D000150:Acinetobacter / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D018441:Biofilms; D010957:Plasmids / Q000235:genetics* / Q000378:metabolism; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism
chemical_list: D001618:beta-Lactamases; C552864:beta-lactamase NDM-1