影响多粘菌素B对绿脓杆菌杀菌效力的主要环境因素的研究

本文通过改变温度,水活度,气体条件和营养含量等影响绿脓杆菌生长的主要环境因素,测定多粘菌素B对绿脓杆菌的最小杀菌浓度(MBC)。结果表明环境因素导致或显著影响绿脓杆菌对抗生素的生态耐受性。实验表明多粘菌素B对绿脓杆菌的杀菌效力,除药物对细菌特有的药理学作用外,还取决于细菌的生长环境。结合冷休克率试验表明,环境影响细菌群体处于分裂状态的菌数。若分裂状态菌数下降表明生长速度减慢。提示了多粘菌素B对绿脓杆菌的效力指数,定量分析可以作为其综合效力作用的表现。以同步培养法确定在单个细胞周期中的抗生素敏感阶段。同时以冷休克率试验资料证明细菌处于分裂状态和幼龄期是其敏感阶段。初步阐述了生长速度缓慢与药物的生态耐受性密切相关。

Studies of Environmental Effects Inducing Change of Pseudomonas aeruginosa Susceptibility to Polymyxin B

In this paper, environmental factors affecting action of polymyxin B were tested through changing nutrients,activity of water in the medium and the temperature as well as air condition in the culture. Polymyxin B MBC to P. aeruginosa was estimated at an effective level. It is true that P. aeruginosa was shown to change its tolerance to polymyxin B as a result of unsuitable environments. This is what we mentioned phenotypic tolerance. Phenotypic tolerance can be brought about by modulations of bacterial growth,eg. by growing slowly. Effect on killing bacteria by an antibiotic depends on the microecological condition aside from the pharmacologic effect of the drug to specific bacteria in testing. The index of efficacy involved in these experiments by analysis of killing P. aeruginosa with polymyxin B index of efficacy combining with cold shock rate it is easy to estimate the bacteriocidal effect of an antibiotic. The technique of synchronous culture was used to assay periods or phases of growth of P. aeruginosa in relation to its susceptibility to polymyxin B in the growth cycle. It appeared that the period of logrithmic phase of growth at 55-65 minutes was more suceptible than others. Cold shock rate showed that in this period bacteria were very young cells and in active fission.