The molecular basis of the epidemic blaKPC gene Klebsiella

描述（由申请人提供）：最近的报告表明，在美国，特别是纽约大都会区和其他地方，碳青霉烯耐药肺炎克雷伯菌（KPC）引起的感染有所增加，这引起了临床医生、感染控制团队和公共卫生官员的注意。KPCs通常表现出广泛的抗菌素耐药性，在某些情况下表现出泛耐药，从而严重影响治疗方案和结果。一个令人不安的方面是，抗性决定因子blaKPC位于可传播质粒上的转座子上。这些携带抗性的质粒已经传播给其他细菌属，如大肠杆菌。因此，了解传播的性质和遗传基础以及这些抗性决定因素的获得是至关重要的。本研究的目的是确定菌株、质粒和转座子在KPC和其他属之间传播和出现blaKPC的作用。这些研究将在纽约地区进行，这里是目前美国和全球KPC菌株的震中。我们将在两个连续的横断面研究（第1年和第4年）中描述KPC流行的性质和程度，以检查5年项目期间感染分离株的分子流行病学，包括其他新兴的碳青霉烯类耐药肠杆菌科。这些研究将涉及广泛的分离物的分子特征，耐药移动元件和决定因素的物理和遗传定位，包括评估碳青霉烯酶活性，并确定中性粒细胞感染模型中循环菌株的相对毒力。为了确定主要的KPC克隆或携带blakpc的质粒是否具有独特的基因组内容或组织，我们将对主要的KPC菌株及其质粒进行从头全基因组测序（WGS）。此外，为了研究当前流行克隆的进化轨迹（扩展和多样化），我们将使用克隆特异性参考菌株对主要KPC菌株进行高通量比较WGS。从KPC菌株和碳青霉烯耐药肠杆菌科、携带blaKPC的质粒、转座子和其他耐药决定因素的分子流行病学研究中获得的信息将有助于评估KPC菌株是由原发（克隆）传播还是获得性耐药的程度，以及在这一高发地区是否出现了新的基因型。我们的中性粒细胞研究将确定宿主-病原体相互作用是否在当前基因型的过度代表中发挥作用。基因组研究的结果可能有助于阐明导致KPC优势克隆传播的因素，这些克隆目前正在助长这种流行病。此外，对主要菌株的深度分子解剖将揭示遗传多样化模式和克隆出现。实现这些目标将通过详细了解发展中危机中心的KPC分离株的分子和遗传特征，加深我们对关键公共卫生问题的理解；评估流行毒株的相对毒力；并通过检测blaKPC基因向肠杆菌科其他成员的横向转移，这些事件将显著阻碍治疗和感染控制计划。这些数据可以为当前和未来的控制战略以及快速诊断的发展提供信息。

DESCRIPTION (provided by applicant): Recent reports indicating a rise in infections caused by carbapenem- resistant Klebsiella pneumoniae (KPC) in the United States, specifically the New York metropolitan area, and elsewhere have alerted clinicians, infection control teams and public health officials. KPCs typically exhibit a wide spectrum of antimicrobial resistance, and pan-resistance in some cases, thereby severely impacting treatment options and outcomes. A troubling aspect is that the resistance determinant, blaKPC is on a transposon that is harbored on transmissible plasmids. These resistance bearing plasmids have transmitted to other bacterial genera, such as E. coli. Therefore, it is critical to understand the nature and the genetic basis of spread and the acquisition of these resistance-determining elements. The goal of the present proposal is to determine the role of strains, plasmids, and transposons in the spread and emergence of blaKPC among KPC and other genera. These studies will be done in the New York area, the current epicenter of KPC strains in the US and globally. We will characterize the nature and extent of the KPC epidemic in two consecutive cross-sectional studies (years 1 and 4) to examine the molecular epidemiology of infecting isolates over the 5-year project period, including other emerging carbapenem-resistant Enterobacteriaceae. These studies will involve extensive molecular characterization of the isolates, physical and genetic mapping of resistance bearing mobile elements and determinants, including evaluating carbapenemase activity, and determining the relative virulence of circulating strains in a neutrophil model of infection. To determine whether predominant KPC clones or blaKPC-harboring plasmids have unique genomic content or organization we will conduct de novo whole genome sequencing (WGS) of major KPC strains and their plasmids. In addition, in order to examine the evolutionary trajectories (expansion and diversification) of the current epidemic clones we will perform high- throughput comparative WGS of major KPC strains using clone-specific reference strains. The information gained from the molecular epidemiologic studies on KPC strains and carbapenem-resistant Enterobacteriaceae, blaKPC -harboring plasmids, transposons and other resistance determinants will help evaluate the extent to which KPC strains are attributed to primary (clonal) transmission or acquired resistance and whether any new genotypes are emerging in this high incidence region. Our neutrophil studies will determine whether host-pathogen interaction play a role in the current overrepresentation of genotypes. The results from the genomic studies may help elucidate factors that contribute to the dissemination of predominant clones of KPC that are currently fueling the epidemic. Furthermore, deep molecular dissection of major strains will indicate patterns of genetic diversification and demonstrate clonal emergence. Accomplishing these aims will deepen our understanding of a critical, public health problem by detailing the molecular and genetic characteristics of KPC isolates in the epicenter of a developing crisis; assessing the relative virulence of circulating strains; and by examining the lateral transfer of blaKPC genes to other members of Enterobacteriaceae, events that would significantly hinder treatment and infection control programs. These data can inform current and future control strategies and in the development of rapid diagnostics.