镓对恶性血液病粒缺患者中铜绿假单胞菌的杀菌活性及其机制研究

All patients with hematological malignancies are susceptible to contracting a nosocomial infection. Appropriate antibacterial therapy can improve the prognosis, however, multidrug-resistant Pseudomonas aeruginosa infections pose serious challenges to treatment. Since iron is critical for bacteria to grow and cause infection, targeting bacterial iron acquisition is therefore a promising therapeutic strategy. Our preliminary work indicates that gallium ion has bactericidal activity against P. aeruginosa and can increase Reactive Oxygen Species (ROS) production. So we speculate that the molecular mechanisms of gallium's bactericidal effect have connection with ROS pathway. In order to know its infection characteristics, we are going to study the resistant phenotype and genotype of epidemic strains in Suzhou area. Simultaneously we will systemically evaluate multiple gallium-antimicrobial combinations for synergistic antimicrobial effect. The combinations that show maximal synergistic effect will be further evaluated for pharmacokinetics, pharmacodynamics, and therapeutic efficacy in a rabbit tissue cage model of infection. In another arm of studies, we will be to first select gallium-resistant and gallium-tolerant mutants. Comparison of whole genome sequences between wild-type and the resistant/tolerant strains, transcriptom analysis in the presence/absence of gallium and between wild-type and mutant strains, and evaluation of the effect of deficiency in ROS detoxification pathway genes on gallium susceptibility will be used to explore and elucidate molecular mechanisms underlying gallium antimicrobial effect. The outcome of the present work will form knowledge base for developing gallium-containing antimicrobial regimens that help overcome the growing problem of nosocomial infection by multidrug resistant P. aeruginosa.

恶性血液病粒缺患者是医院内感染的高危人群,恰当的抗感染治疗可改善患者预后,而多重耐药铜绿假单胞菌给治疗带来严峻挑战。铁是细菌生存和感染的必需元素,切断铁的获取能抑制细菌生长,铁类似物镓有可能通过干扰铁代谢途径成为有前景的抗菌策略。本课题组预实验表明:镓对铜绿假单胞菌有杀菌活性;且镓能够上调细菌活性氧的产生,由此我们推测镓杀菌的分子机理与ROS通路有关。本课题拟收集苏州地区恶性血液病粒缺患者院内感染的多重耐药铜绿假单胞菌,了解其耐药表型及克隆传播等特征;同时系统探索镓-抗菌药物组合的协同杀菌效应,并在兔组织笼模型中进行药代药效动力学及疗效验证;然后筛选出镓耐药/耐受突变体,对比野生型进行全基因组及转录组测序,寻找镓作用的靶基因,进行靶基因的表达分析,并构建ROS解毒通路基因缺失株,检测对镓杀菌敏感性的影响,阐明镓杀菌的分子机理,为开发新型含镓抗菌药物,防治铜绿假单胞菌的院内感染提供新思路。

恶性血液病粒缺患者是医院内感染的高危人群，恰当的抗感染治疗可改善患者预后，而多重耐药铜绿假单胞菌给治疗带来严峻挑战。铁是细菌生存和感染的必需元素，切断铁的获取能抑制细菌生长，铁类似物镓有可能通过干扰铁代谢途径成为有前景的抗菌策略。本课题实验表明:镓对铜绿假单胞菌有杀菌活性;且镓能够上调细菌活性氧的产生,镓杀菌的分子机理与ROS通路有关。本课题收集苏州地区恶性血液病粒缺患者院内感染的多重耐药铜绿假单胞菌，了解其耐药表型及克隆传播等特征;同时系统探索镓-抗菌药物组合的协同杀菌效应,并在兔组织笼模型中进行药代药效动力学及疗效验证;然后筛选出镓耐药/耐受突变体,对比野生型进行全基因组及转录组测序,寻找镓作用的靶基因,进行靶基因的表达分析,并构建ROS解毒通路基因缺失株,检测对镓杀菌敏感性的影响,阐明镓杀菌的分子机理,为开发新型含镓抗菌药物, 防治铜绿假单胞菌的院内感染提供新思路