【作者】 王平；

【导师】 田德英；

【作者基本信息】 华中科技大学 ， 内科学， 2010， 博士

【摘要】 [目的]从临床角度出发，排除人为因素影响，研究临床野生铜绿假单胞菌致病能力，探讨密度感应系统(Quorum Sensing, QS)与铜绿假单胞菌致病性的关系，为QS系统群体控制理论提供新信息，为临床控制铜绿假单胞菌感染提供第一手资料，为临床控制铜绿假单胞菌感染寻找新的治疗策略。[方法]以铜绿假单胞菌临床感染特征及对策为研究方向，以铜绿假单胞菌临床分离株为研究对象，分析铜绿假单胞菌临床感染分布特点、耐药规律；检测QS系统功能缺陷时铜绿假单胞菌毒力因子表达变化情况；检测QS系统编码基因突变特点，分析QS系统对毒力因子表达调控机制。[结果]1、本研究的铜绿假单胞菌感染在呼吸道最为突出；在ICU最为多见；铜绿假单胞菌耐药问题严重，有多重耐药，与目前大多数研究结果基本一致。2、本研究检测84株铜绿假单胞菌临床分离株，95．34％的菌株QS系统功能正常，QS系统功能缺陷株检出率只有4．76％。3、QS系统功能缺陷株多种毒力因子表达均有不同程度的障碍，QS系统对铜绿假单胞菌各致病因子表达或严格控制，或部分调控。QS系统严格调控弹性蛋白酶分泌，QS系统是绿脓菌素分泌、生物被膜形成和泳动能力调控机制之一。4、在铜绿假单胞菌QS系统中，rh1系统参与了弹性蛋白酶表达、绿脓菌素分泌、生物被膜形成和泳动能力调控。5、临床分离铜绿假单胞菌QS系统功能缺陷株QS系统编码基因发生突变(包括基因缺失和或点突变)，许多突变位点相同。[结论]1、铜绿假单胞菌临床分离株绝大多数QS系统功能正常，少数QS系统功能缺陷，QS系统功能缺陷株致病能力减弱，说明QS系统在铜绿假单胞菌临床感染的过程中发挥了重要作用，干扰铜绿假单胞菌OS系统可能是一种非常有希望的新治疗手段。2、铜绿假单胞菌QS系统功能缺陷株致病能力减弱，但QS系统功能缺陷并未导致铜绿假单胞菌致病能力完全丧失，干扰铜绿假单胞菌QS系统不能完全清除感染，细菌可利用自身及环境中的一切有利因素生存，控制铜绿假单胞菌感染可能需要多种手段联合使用。3、铜绿假单胞菌致病性强弱受包括QS系统在内的复杂网络调控，宿主个体差异、内环境、免疫功能状态等因素在铜绿假单胞菌建立感染过程中的作用不容忽视。4、铜绿假单胞菌QS系统编码基因存在突变高发区。更多还原

【Abstract】 Objective This paper studied the pathogenic capabilities of clinical wild PA strains and probed the relationship between the QS system and the pathogenicity of PA from a clinical point of view. New information for group control theory of the QS system, first-hand material for clinical control of PA infection, toy and to new strategies for clinical control of PA infection are provided in this study.Methods By using the characteristics and countermeasures of PA clinical infection as the research direction, and clinically isolated PA strains as the research objects, we,,analyzed the distribution characteristics and drug resistance of PA clinical infection, we also tested changes of PA virulence factors expression upon the QS system failure. The encoding gene mutation features of QS system and the regulation mechanisms of QS system to virulence factors were also investigated.Results 1. The drug resistance and clinical distribution of PA in the Wuhan region are consistent with results reported by other researches.2. In 84 clinical isolated PA strains, most (95.34%) show normal QS system.. We have screened out four QS defective strains (4.76%).3. The expressions of various virulence factors of these defective strains are all defective to different extent, and QS system control strictly or partially the pathogenesis of PA.. Elastase secretion is strictly regulated by the QS system. Pyocyanine secretion, bacteria biofilm formation and swimming ability are regulated by QS system 4. RHL system plays an important role in the secretion of pyocyanine. Biofilm formation and swimming ability are also regulated by RHL system.5. PA QS system exists highly mutation-prone region. The coding genes of local PA QS system are not identical with those of wild standard strains.Conclusion 1. The functions of QS system in most clinically isolated PA strains is normal, and it suggests that QS system plays an important role in the process of clinical PA infection. Interference with QS system could be a very promising new treatment, which deserves further study.2. The pathogenic ability of QS defective strains flaws, but they can still establish infections. The defection of QS system doesn not completely disable the pathogenesis. Interfering with PA QS system cannot completely remove bacterial infection, and the bacteria can survive through all the favorable elements, and to control PA infection may need to use a combination of all kinds of means.3.The strength of PA pathogenic ability is regulated by a complex network including the QS system. The effect of the individual differences in the host, internal environment factors, and the immune function cannot be ignored when PA establishes infections.4.The encode gene of QS system exits a highly mutational area.更多还原