铜绿假单胞菌多粘菌素异质性耐药机制研究

Pseudomonas aeruginosa is one of the most important hospital acquired pathogens, and its multidrug resistant situation is severe. Colistin is the nominated antibiotic for treatment of multidrug resistant, extensively-drug resistant and pandrug resistant bacterial infections. Although Pseudomonas aeruginosa is quite susceptible to colistin in the current time, its heteroresistance to colistin has caused more and more concerns. In our previous study, we found that the heteroresistance rate in colistin susceptible- and carbapenem resistant-Pseudomonas aeruginosa had been up to 35%, while its true mechanism was still unknown. In this study, We would choose colistin-heteroresistant Pseudomonas aeruginosa and its colistin-resistant subpopulations as the objects, to identify the heteroresistant mechanism by analysis of LPS and lipid A modifications, mutation and expression level changes of two component regulatory systems; to clarify the correlation of heteroresistant mechanism with resistant mechasim by analysis of phenotypic stability and homogeneity of heteroresistant subpopulations, and meanwhile analyze whether the heteroresistant phenotype would change to resistance after doses of drugs in vitro and in vivo; to explore new mechanism of heteroresistance through constructing transposon library and whole genome sequencing of heteroresistant subpopulations. The results of this study would provide new knowledge for preventing Pseudomonas aeruginosa from colistin heteroresistance to homogeneous resistance.

铜绿假单胞菌是重要条件致病菌及院内感染病原菌之一，其多重耐药现状十分严峻。多粘菌素是目前治疗多重耐药革兰阴性菌感染的最后防线。现有研究表明：虽然铜绿假单胞菌对多粘菌素的敏感性较高，但其异质性耐药问题十分严重。本课题组前期研究发现：碳青霉烯类耐药铜绿假单胞菌对多粘菌素的异质性耐药率高达35%，但其机制及对耐药发展的影响仍不明确。本课题组拟以多粘菌素异质性耐药铜绿假单胞菌及其耐药亚群为研究对象，研究LPS和脂质A成分的变化及双组分调控系统的基因突变和表达量改变与异质性耐药的关系，明确异质性耐药机制；通过分析异质性耐药亚群的表型稳定性和均一性，同时分析异质性耐药菌株在体内外经药物作用前后的耐药性是否转变，阐明异质性耐药与耐药的相关性；通过突变体库和全基因组等方法对未明机制的异质性耐药亚群进行分析，以期发现新的机制。本研究结果将为多粘菌素的临床合理应用和多粘菌素耐药性的防控提供科学基础。