| Summary: | 碩士 === 國立交通大學 === 環境工程所 === 87 === The Effects of Antibiotics on Mixture Toxicity
to Staphylococcus aureus
Student: Yeh Shu-Hao Advisor: Dr. Chen Chung-Yuan
Institude of Environmental Engineering
National Chaio Tung University
ABSTRACT
E. coli and P. phosphorium were used as laboratory bacterium in the past to conduct mixture toxicity research of organic toxins. The toxic mechanism of the organic toxins and the slope of the dose-response curve were used as main grouping tools to generalize a conclusion. When a small slope rate appeared on the dose-response curve while toxic materials were under different mechanism conditions, the proportion of synergism produced was very high.
This research used Staphylococcus aureus as the laboratory bacterium, chose twenty-nine types of antibiotic, and divided into five categories based on its bacteria-suppressing mechanism. The post-categorized results were used to proceed mixture toxicity testing of the agar plate test, and to observe its growth-suppression situation of the Staphylococcus aureus, as well as discussing prediction method of the mixture toxicity model and to make comparison with previous test results done on organic toxic materials using turbidity method, together with checking the applicability of prediction principles between different objects and different toxic materials, in addition to comparing test results derived from turbidity method and time-kill curve, with the agar plate test result.
The agar plate test result of this research indicated that although the two mechanisms had different functions, the highest possibility of synergism, as high as 80%, was produced under the combination of antibiotics when the slope rate of the dose-response cure was smaller than 1. At the same time, the mixture antibiotic test result using turbidity method and time-kill curve was consistent with the result derived from the agar plate test. When making a comparison between these three mixture toxicity tests, the agar plate test was more convenient as well as capable of conducting multiple testing at one time; time-kill curve allowed us to understand the actual suppression situation of the bacterium, and was consistent with the turbidity method, able to substantiate the feasibility of applying toxicology to pharmacology.
The use of the similarity between toxicology and pharmacology, allowed this research result to effectively predict the model of combined effects. Its application in pharmacology can be applicable on controlling bacterium infections. Today''s medical field commonly faces bacteria capable of high-tolerance, in addition to some of the bacteria unable to be suppressed by a single antibiotic, hence for the research on mixture antibiotic testing, an urgently needed and workable method. The main objective of this research is to combine two types of antibiotics, and for them to form effective treatment by producing synergism.
Key words : Staphylococcus aureus, turbidity method, agar plate test, time-kill curve, dose-response curve, synergism.
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