碳青霉烯耐药肺炎克雷伯菌替加环素耐药机制研究

Carbapenem-resistant Klebsiella pneumonia(CRKP) infection has became a big challenge in the field of anti-infection. By far, the anti-infection drugs for CRKP infection are limited, and tigecyclne become very important in CRKP treatment. However the problem of tigecycline resistance is worsening. Tigecycline resistance often occurs during clinical use. The mechanisms of tigecycline resistance are still not fully understood. Our previous studies found that over expression of RND type efflux pump AcrAB was one of the major mechanisms in tigecycline resistance in CRKP. We also found multiple mechanisms (Mla system, efflux pump, and ribosomal S10 protein) can accumulate gradually in the development of tigecycline resistance in laboratorial strain. However, the resisitance mecheanism in vivo is still not clear. This study will continue collecting CRKP strains in patients who under tigecycline treetment. We will use various methods including whole genome sequencing, comparative genomics, gene knockout and complementation tests to clarify the mechanisms and process of tigecycline resistance in these clinical strains. It will provide experimental basis for the clinical rational use of tigecycline and efficiency treatment of CRKP infection. The study will provide a scientific basis to control tigecycline resistance as well.

碳青霉烯耐药肺炎克雷伯菌（CRKP）感染是抗感染领域面临的严峻问题。CRKP感染不断增加，有效治疗药物极少。替加环素是目前临床治疗CRKP感染的重要抗菌药物，但其耐药问题日趋严重，替加环素耐药的报道快速增加，尤其是在治疗过程中菌株从敏感发展成为耐药，其确切机制仍不明确。本课题组前期研究发现：RND型外排泵AcrAB高表达是导致CRKP替加环素耐药的主要机制之一；在替加环素体外诱导耐药菌株里，我们发现替加环素耐药的发展是Mla系统、外排泵系统和核糖体蛋白变异三种机制共同参与的结果，但体内耐药发生机制仍不清楚。本研究将收集CRKP感染患者替加环素治疗过程中各个阶段分离的细菌，针对耐药进展菌株运用高通量全基因组测序、比较基因组学分析、基因敲除和回补等方法，阐明CRKP替加环素耐药发展的过程及具体机制；为临床合理使用替加环素，提高CRKP感染疗效提供科学基础；为延缓和控制替加环素耐药提供理论依据。

碳青霉烯耐药肺炎克雷伯菌（CRKP）感染是抗感染领域面临的严峻问题，替加环素是目前临床治疗CRKP感染的重要抗菌药物，对替加环素体内耐药机制的阐明是延缓和控制替加环素耐药的重要基础。本项目中，我们通过对最新收集的CRKP菌株展开研究，发现在CRKP的替加环素耐药中，外排泵AcrAB系统的高表达（包括调控基因的突变）和核糖体蛋白基因rpsJ的突变仍旧是主要的机制。我们通过对多例CRKP感染，然后在替加环素治疗过程中产生耐药的病例展开研究，发现替加环素治疗CRKP感染存在失败的风险，在治疗过程中CRKP可快速出现由四环素耐药基因tetA突变介导的耐药，并且这种耐药可通过质粒进行水平转移，进而增加了传播性和威胁性，tetA突变并向替加环素耐药演变越多，它就越有可能成为替加环素重要水平转移耐药基因，而这一现象的出现，必然会对替加环素的使用寿命构成威胁。另外在替加环素持续治疗压力下，在体内环境可快速出现由核糖体蛋白基因（rpsJ）突变介导的耐药，由于rpsJ基因存在于细菌染色体上，因此在替加环素的选择性压力下，CRKP菌株极有可能发生rpsJ基因突变进而导致替加环素耐药，并最终导致临床治疗的失败，因此选择合适替加环素剂量及联合治疗方案可能有助于CRKP感染临床疗效的提高，同时减少耐药的发生。