Identification of new or unrecognized virulence genes in hypervirulent Klebsiella pneumoniae and antivirulence genes in classical K. pneumoniae.

项目摘要/摘要： 一种超强毒力肺炎克雷伯氏菌(HvKp)正在全球传播。与之形成鲜明对比的是 典型肺炎克雷伯菌(CKP)感染通常与医疗保健相关的流行病学，hvKp引起组织 社区中其他健康个体的侵袭性感染。感染通常涉及多个部位 需要源头控制(例如，脓肿、坏死性筋膜炎)或需要特定部位治疗的部位 (如眼内炎、脑膜炎)。最初的hvKp菌株对抗生素敏感，但最近的hvKp 菌株一直在获取编码超广谱β-内酰胺酶和碳青霉烯酶的基因。这个 也可能发生转移方向相反的情况。最近从中国分离的一株广泛耐药(XDR)CKP菌株 已经获得了hvKp中存在的部分毒力质粒的ST11序列类型被认为是 重症监护病房爆发致命性疫情的原因。超强毒力XDR病原体的前景极其光明 关于。 这项建议的目标是增加我们对这些因素的有限了解，并产生初步的见解 探讨导致hvKp超强毒力表型的机制。反过来，这将实现合乎逻辑的策略 预防或治疗由这种真正的超级细菌引起的感染。为了实现这一点，我们将利用以前生成的 体内毒力数据开发了准确定义的hvKp和CKP菌株队列。这些研究 鉴定了四个毒株类别：1-具有已知毒力因子(VFS)的典型hvKp菌株和 在体内完全毒力；具有已知VFS但毒力低于原型的2-hvKp菌株 体内的hvKp菌株；3-不具有已知hvKp VFS的原型CKP菌株 与典型的hvKp菌株相比，体内毒力较低；以及不具有已知hvKp基因的4-CKP菌株 与典型的CKP毒株相比，VFS在体内的毒力更强。这些菌株类将被用作 通过基因组测序、序列分析识别编码VFS或抗VFS的候选基因的工具 和对基因组的描述，以及随后的适当比较(目标1)。推定的小说或 未被识别的VFS和抗VFS将被优先考虑，同基因突变和互补的衍生物将被优先考虑 这些结构将在体内肺炎和系统感染模型中进行评估(目标2)。 该提案的可交付成果将是识别新的或未识别的VFS并在体内进行验证 和/或缺乏抗VFS导致hvKp的超强毒力表型。

Project Summary/Abstract: A hypervirulent Klebsiella pneumoniae (hvKp) pathotype is undergoing global dissemination. In contrast to the usual healthcare-associated epidemiology of classical K. pneumoniae (cKp) infections, hvKp causes tissue invasive infections in otherwise healthy individuals from the community. Infection often involves multiple sites that require source control (e.g. abscesses, necrotizing fasciitis) or locations that require site-specific therapy (e.g. endophthalmitis, meningitis). Initial strains of hvKp were antimicrobial susceptible, however, recently hvKp strains have been acquiring genes that encode extended-spectrum ß-lactamases and carbapenemases. The reverse direction of transfer also can occur. Recently an extensively drug-resistant (XDR) cKp strain from sequence type ST11 that had acquired part of a virulence plasmid present in hvKp was implicated as the cause of a lethal outbreak in an intensive care unit. The prospect of a hypervirulent XDR pathogen is extremely concerning. The goal of this proposal is to increase our limited understanding of the factors and generate initial insights into the mechanisms responsible for hvKp’s hypervirulent phenotype. This, in turn, will enable logical strategies to prevent or treat infections due to this true superbug. To accomplish this, we will utilize previously generated in vivo virulence data developed with accurately defined cohorts of hvKp and cKp strains. These studies identified four strain classes: 1- prototypical hvKp strains that possessed known virulence factors (VFs) and were fully virulent in vivo; 2- hvKp strains that possessed known VFs but were less virulent than prototypical hvKp strains in vivo; 3- prototypical cKp strains that did not possess known hvKp VFs and were significantly less virulent in vivo compared to prototypical hvKp strains; and 4- cKp strains that did not possess known hvKp VFs but were more virulent in vivo compared to prototypical cKp strains. These strain classes will be used as “tools” to identify candidate genes that encode VFs or anti-VFs via genomic sequencing, sequence analysis and delineation of gene sets, and subsequent appropriate comparisons (aim 1). Putative novel or unrecognized VFs and anti-VFs will be prioritized, isogenic mutant and complemented derivatives will be generated, and these constructs will be assessed in in vivo pneumonia and systemic infection models (aim 2). The deliverables of this proposal will be the identification and in vivo validation of new or unrecognized VFs and/or lack of anti-VFs that contribute to hvKp’s hypervirulent phenotype.