携带blaNDM-1的质粒pNDM-BJ01在鲁氏不动杆菌中的适应度代价

Fitness costs of blaNDM-1 bearing plasmid pNDM-BJ01 in Acinetobacter lwoffii

摘要:

摘要:【目的】了解编码新德里金属-β-内酰胺酶-1(blaNDM-1)的质粒pNDM-BJ01在鲁氏不动杆菌10621菌株中的适应度代价，进而评估该质粒在鲁氏不动杆菌群体中存续和扩散的潜能。【方法】通过不含亚胺培南的液体培养基连续传代培养，获得抗性质粒丢失的10621衍生菌株，利用生长曲线、生物被膜、无营养生存时间等体外适应度测量实验，分析10621NDM-1(+)及质粒缺失的10621NDM-1(－)之间的适应度差异。【结果】pNDMBJ01在10621 菌株中不稳定，连续传代11次即在群体中完全丢失。在26℃和37℃下，10621NDM-1(－)与10621NDM-1(+)菌株的生长曲线无显著性差异。在26℃条件下，10621NDM-1(－)菌株形成生物被膜的能力明显强于10621NDM-1(+)，而在37℃条件下，10621NDM-1(+)强于10621NDM-1(－)。在无营养的PBS 缓冲液中，10621NDM-1(－)菌株生存能力明显高于10621NDM-1(+)。【结论】编码blaNDM-1的质粒pNDM-BJ01在鲁氏不动杆菌中具有较大的适应度代价，缺失这一质粒的菌株在外界环境中的生存能力强于抗性菌株，pNDM-BJ01在鲁氏不动杆菌存续与扩散的能力有限。

Abstract:

Abstract:［Objective］To investigate the fitness costs of the New Delhi Metallo-β-lactamase-1 (blaNDM-1) bearing plasmid pNDM-BJ01 in Acinetobacter lwoffii strain 10621，and to evaluate the potentials of the sustainability 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 10621NDM-1(+) 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°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°C，whereas the latter showed higher ability of biofilm formation at 37°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.［Conclusion］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.