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

项目概要/摘要： 一种高毒力肺炎克雷伯菌（hvKp）致病型正在全球传播。相比 常见的卫生保健相关流行病学经典K。肺炎（cKp）感染，hvKp导致组织 来自社区的其他健康个体的侵袭性感染。感染常累及多个部位 需要源头控制（如脓肿、坏死性筋膜炎）或需要特定部位治疗的部位 (e.g.眼内炎、脑膜炎）。最初的hvKp菌株对抗菌药物敏感，然而， 菌株已获得编码超广谱β-内酰胺酶和碳青霉烯酶的基因。的 也可能发生反向转移。最近，一种广泛耐药（XDR）的cKp菌株来自 已经获得存在于hvKp中的毒力质粒的一部分的序列类型ST 11被认为是 重症监护室致命疾病爆发的原因超毒力XDR病原体的前景是极其 关于 本提案的目标是增加我们对这些因素的有限理解，并产生初步见解 hvKp高毒力表型的机制。这反过来将使逻辑策略 来预防或治疗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 用准确定义的hvKp和cKp菌株群开发的体内毒力数据。这些研究 鉴定了四种菌株类型：1-具有已知毒力因子（VF）的原型hvKp菌株， 具有已知VF但毒性低于原型的2- hvKp菌株 体内hvKp菌株; 3-原型cKp菌株，其不具有已知的hvKp VF，并且显著地 与原型hvKp菌株相比，体内毒性较低;以及不具有已知hvKp的4- cKp菌株 VF，但在体内比原型cKp菌株更具毒性。这些菌株类别将用作 通过基因组测序、序列分析和基因组测序鉴定编码VF或抗VF的候选基因的“工具” 和基因组的描绘，以及随后的适当比较（目的1）。小说或 未识别的VF和抗VF将被优先考虑，同基因突变体和互补衍生物将被 产生，并且这些构建体将在体内肺炎和全身感染模型中进行评估（目的2）。 本提案的可交付成果将是新的或未识别VF的识别和体内验证 和/或缺乏有助于hvKp的高毒力表型的抗VF。

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.