| Popis: |
The worldwide emergence and spread of antibiotic resistant bacteria represent a major threat to human health care as the chance of therapy failure and costs for treatment increase. To curb the continuous rise of drug resistant bacteria worldwide, new strategies are urgently needed that counteract the development and spread of resistance. Development of innovative countermeasures depends on a deeper understanding of how sensitive and drug resistant bacteria respond to different drug levels, circumvent metabolic costs and the development of knowledge of the factors that can affect the acquisition of drug resistance. Therefore, the main object of this thesis was to characterize and quantify the relationship between antibiotic usage and development and transmission of resistance using laboratory cultures of E. coli as a model. The genetic and physiological changes that were shown in this study to accompany the acquisition of resistance indicate that bacteria are able to acquire resistance and compensate for metabolic costs due to various and highly flexible strategies. In addition, in vitro conjugation rates of a plasmid that confers antibiotic resistance and that originated from a food isolate was dependent on cell density, energy availability, growth rate and antibiotic concentration. The outcome of this thesis contributes to the current knowledge regarding the development and spread of resistance in bacteria and could be used as basis for further studies on molecular regulatory mechanisms involved in the acquisition of antibiotic resistance. |
