The role of commensal organisms as pro-infectious agents in Staphylococcus aureus infection dynamics.

金黄色葡萄球菌是一种重要的人类病原体，在世界各地造成重大的死亡和疾病。耐甲氧西林金黄色葡萄球菌(MRSA)等耐抗生素菌株的传播加剧了这一问题。MRSA通常是一种医院相关感染，但最近社区获得性MRSA在明显缺乏抗生素选择的情况下有所增加。因此，一直需要开发新的金黄色葡萄球菌控制机制，因为这种生物已经开始对利奈唑胺等新抗生素表现出抗药性，而且没有疫苗可用。为了赢得这场战斗，我们不仅必须制定新的治疗方法和预防措施，而且还必须了解金黄色葡萄球菌致病原因的复杂性，从而了解如何最好地利用干预措施，以减少疾病负担，并将抗药性的发展和传播降至最低。人类是如何感染金黄色葡萄球菌的？我们有了一个惊人的发现，相对无害的皮肤生物，甚至它们的组成细胞壁，都能够导致金黄色葡萄球菌感染的显著恶化，使疾病发生时感染剂量大大减少。人类最常见的感染途径是通过伤口，当然，任何物质进入体内都会发生这种情况，包括金黄色葡萄球菌。我们已将能增强金黄色葡萄球菌感染的物质命名为“促感染剂”。我们为自然感染打开了一扇窗，并通过这样做为试图了解疾病以及我们如何预防疾病提供了新的途径。目前的应用采用跨学科的方法，以了解感染是如何启动的，可以作为促染剂的材料和生物体的性质，感染是如何进展的，以及如何利用这些知识来预防和/或治疗疾病。我们的背景工作和这项提议需要一个由一名微生物学家和一名具有天然免疫研究专业知识的临床医生领导的综合团队。这种结合的专业知识，加上世界各地的重要合作伙伴，为我们雄心勃勃的计划提供了一个经过验证的网络。我们的工作以使用动物感染模型为基础，因为如果不了解体内发生的情况，这个复杂的过程无法在体外重述。我们独一无二地发展了脊椎动物斑马鱼胚胎，作为金黄色葡萄球菌系统性疾病的模型。这提供了一个高通量、遗传上易于处理的系统，其中可以在活的宿主中观察到宿主与病原体的相互作用。这个模型的重要之处在于，它不仅为发病机制提供了重要的见解，而且还为我们提供了使用哺乳动物系统的信息，从而直接取代了许多小鼠实验，减少了使用的哺乳动物数量，并改进了我们的方法。我们将使用动物模型和体外分析相结合的方法来确定可以增强金黄色葡萄球菌感染的材料的广度，以及这种影响的细胞和分子机制。然后，将从开始到终点绘制感染情况图，以便确定瓶颈，作为制定新干预策略的地点。我们将在所有模型中使用包括最先进的活体显微镜在内的各种方法来确定感染的途径。应用程序提供了一个集成的包，将进一步加深我们对疾病机制的理解，以及如何将这些信息用于指导临床实践。

Staphylococcus aureus is an important human pathogen that causes significant death and disease around the world. The problem is exacerbated by the spread of antibiotic resistant strains such as Methicillin Resistant S. aureus (MRSA). MRSA is generally a hospital-associated infection but recently community acquired MRSA has increased in the apparent absence of antibiotic selection. Thus there is a constant need to develop new control regimes for S. aureus, as this organism has begun to show resistance even to new antibiotics such as linezolid and no vaccine is available. To win this battle we must not only produce new treatments and preventative measures but also to understand the complexities of how S. aureus causes disease and thus how interventions can be best utilised, to reduce the disease burden and to minimise the development and spread of resistance to antibiotics. How do humans get infected with S. aureus? We have made the astonishing discovery that relatively harmless skin organisms and even their component cell walls are able to cause significant exacerbation of S. aureus infection, allowing disease to occur with a hugely reduced infectious dose. The most common route of human infection is via a wound and of course this will occur with whatever material gets in, including S. aureus. We have named the material that can augment S. aureus infection as "pro-infectious agents". We have opened a window on natural infection and in doing so provide novel avenues for trying to understand disease and how we may prevent it. The current application takes an interdisciplinary approach to understand how infection is initiated, the nature of material and organisms that can act as pro-infectious agents, how infection progresses and how such knowledge may be utilized to prevent and/or cure disease. Our background work and that proposed necessitates an integrated team led by a microbiologist and a clinician with research expertise in innate immunity. This combined expertise, coupled with important partners around the world, provides a proven network to underpin our ambitious proposal.Our work is underpinned by the use of animal models of infection, as this complex process cannot be recapitulated in vitro without understanding of what happens in vivo. We have uniquely developed the vertebrate zebrafish embryo as a model of S. aureus systemic disease. This provides a high-throughput, genetically tractable system where host:pathogen interaction can be observed in a living host. The importance of this model is that it has not only provided important insights into pathogenesis but has also informed our use of a mammalian system thus replacing many mouse experiments directly, reducing the numbers of mammals used and refining our approach. We will use a combination of animal models, together with in vitro analysis to determine the breadth of material that can augment S. aureus infection and the cellular and molecular mechanisms underlying this effect. Infection will then be mapped from initiation to endpoint in order to identify bottlenecks as sites for the development on novel intervention strategies. We will use a variety of approaches including state-of-the-art intravital microscopy in all models to determine the pathway of infection.The application provides an integrated package that will further our understanding of disease mechanisms and how this information may be used to inform clinical practice.