Biology of hypervirulent Klebsiella pneumoniae translocation from the gastrointestinal tract

描述。 肺炎克雷伯菌(Kpn)是医院获得性感染的重要来源。由于KPN已经收购了多家 耐药，它的治疗变得更加具有挑战性。另一个令人担忧的问题是隔离的增加 已知可引起肺炎克雷伯氏菌或hvKpn超强毒力的菌株 社区环境。这些分离株已经获得了一系列毒力因子，这使得它们能够引起 免疫能力强的人患上的疾病。最近，多起致命的医院疫情与多起 耐药hvKpn分离株。流行病学研究表明，hvKpn的胃肠道定植是 一种主要的蓄水池，通过它可以转移到无菌的地方，并在 被殖民的主人。然而，hvKpn肠道定植并不是以前研究的重点，作为一个可驯化的模型。 胃肠道(GI)无定植和移位。我们最近开发了一种小鼠模型 Kpn和hvKpn GI定植，不需要抗生素。我们的易驾驭模型允许 我们更好地了解KPN与具有完整肠道微生物群的宿主的动态相互作用。 此外，还观察到化脓性肝脓肿的发展，这是人类感染hvKpn的标志。 在我们的GI殖民模型中。因此，我们建议hvKpn通过特定的途径来促进其 易位，由其毒力决定因素促进。这些决定因素可以作为新的目标 预防疾病状态的发展。 体外细胞分析确定hvKpn促进其易位的途径(S)。其次，我们将 利用基因敲除小鼠品系确定宿主M细胞在促进hvKpn易位中的作用。我们的数据显示 HvKpn特异的铁摄取分子好氧肌动蛋白(IUC)参与了转位过程。 即使IUC在易位中起作用，IUC突变体也不能完全消除它，这表明其他 这些因素是易位的关键因素。通过在目标2中采用体内新的高通量方法，我们将 确定可能促进其易位的hvKpn因子。我们的研究结果不仅将提供 了解易位过程，也确定假定的易位决定因素，这可能是 降低hvKpn疾病负担的潜在目标。

Description. Klebsiella pneumoniae (Kpn) is a significant source of hospital-acquired infections. As Kpn has acquired multi- drug resistance, it has become even more challenging to treat. Another concern is the increase in isolation of strains termed as "hypervirulent" Klebsiella pneumoniae or hvKpn known to cause disease manifestations in a community setting. These isolates have acquired a repertoire of virulence factors, which allow them to cause disease in immunocompetent individuals. Recently, multiple fatal hospital outbreaks have been linked to multi- drug resistant hvKpn isolates. Epidemiological studies suggest that gastrointestinal (GI) colonization of hvKpn is a major reservoir through which it can translocate to sterile sites and cause disease manifestations in the colonized host. However, hvKpn gut colonization has not been the focus of previous studies as a tractable model for gastrointestinal (GI) colonization and translocation did not exist. We recently developed a murine model of Kpn and hvKpn GI colonization, achieved without the requirement of antibiotics. Our tractable model allows us a better understanding of the dynamic interactions of Kpn with the host with an intact gut microbiome. Moreover, development of pyogenic liver abscess a trademark of hvKpn infections in humans was also observed in our GI model of colonization. Thus, we propose that hvKpn uses specific pathways to promote its translocation, facilitated by its virulence determinants. These determinants can serve as novel targets for the prevention of the development of the disease state. More recently, with our animal model, we observed translocation to occur 24 hours post-GI colonization. However, the exact route(s) taken by hvKpn and the role of specialized enterocytes (M-cells) in translocation remains to be elucidated. Thus, in Aim #1, we will carry out in vitro cell line assays to determine the pathway(s) taken by hvKpn to promote its translocation. Secondly, we will determine the host M-cells' role in promoting hvKpn translocation using knockout mice strains. Our data suggest that hvKpn specific iron acquisition molecule aerobactin (iuc) contributes towards the translocation process. Even though iuc plays a role in translocation, an iuc mutant does not entirely abrogate it, suggesting that other factors are critical for translocation. By taking an in vivo novel high-throughput approach in Aim #2, we will identify putative hvKpn factors that promote its translocation. Results from our studies will not only provide an understanding of the translocation process but also identify putative translocation determinants, which could be potential targets to reduce the hvKpn disease burden.