Modeling Staphylococcus aureus antagonism in pediatric nasal communities

 描述(申请人提供)：鼻腔是金黄色葡萄球菌的重要利基。与年龄较大的儿童或成年人相比，幼儿--尤其是那些3岁或3岁以下的儿童--更有可能被金黄色葡萄球菌定植。金黄色葡萄球菌鼻腔定植显著增加了随后感染的风险，但儿童非殖民化战略有限，对莫匹罗星的耐药性正在出现。近年来，金黄色葡萄球菌在儿科人群中的感染率也在稳步上升，尽管成年人的趋势相反。迫切需要对金黄色葡萄球菌采取更好的预防策略，以减少儿科感染。我们的长期目标是开发基于益生菌的策略，以减少金黄色葡萄球菌在儿童中的定植、传播和感染。要做到这一点，我们需要更好地了解儿科鼻部微生物区系的动态和决定因素。这项建议的总体目标是确定在儿科鼻腔环境中可以竞争性排除金黄色葡萄球菌的共生体。基于我们的初步研究，中心假设是竞争性排除非致病性鼻部连结，如Dolosigranulum，可以持久地抵抗金黄色葡萄球菌的定植。拟议研究的基本原理是，更好地了解鼻部微生物区系的稳定性和演替，结合对Dolosigranulum和其他共生体如何与金黄色葡萄球菌相互作用的实验测试，将为鼻部益生菌的潜在有效性提供重要的见解。这项研究的假设将通过两个具体的目标来检验：目标1：确定具有高绝对丰度的特定鼻部共生体的儿童在出生第一年是否携带金黄色葡萄球菌的风险较低；以及目标2：经验地确定Dolosigranulum在一种新的上皮-微生物组培养模型中竞争性排除金黄色葡萄球菌的能力。目标1将使用现有的从一岁婴儿(n=203)的纵向鼻腔样本收集来实现。基线(即1个月)样本将通过基于绝对丰度的微生物组分析来鉴定患有多发性颗粒菌或金黄色葡萄球菌主导的鼻部群落状态类型(CST)的婴儿。将对30名婴儿的微生物演替进行表征，以确定这些CST的动态。为了从实验上评估鼻部细菌竞争，Aim 2将使用来自Aim 1的精选CST的样本构建上皮-微生物组模型，该模型将受到金黄色葡萄球菌和其他鼻部CST的直接挑战。在这个团队看来，这种方法是创新的，因为它将构建和验证一个新的体外模型系统，以概括观察到的鼻部CST，并能够在混合培养环境中对我们的竞争-排除假说进行经验测试。这项拟议的研究意义重大，因为这是一项鼻部益生菌对抗金黄色葡萄球菌的原则验证研究。重要的是，该项目将为未来的宿主-微生物和微生物-微生物研究产生一个有效的模型系统，这将加速发现防止金黄色葡萄球菌定植和感染的新方法。

 DESCRIPTION (provided by applicant): The nasal cavity is an important niche for Staphylococcus aureus. Young children-particularly those age 3 or younger-are more likely to be colonized by S. aureus than older children or adults. S. aureus nasal colonization significantly increases the risk for subsequent infection, but decolonization strategies for children are limited, and mupirocin resistance is emerging. In recent years, S. aureus infection rates have also steadily risen in the pediatric population, despite opposing trends in adults. Better preventative strategies against S. aureus are urgently needed to reduce pediatric infections. Our long-term goal is to develop probiotic-based strategies to decrease S. aureus colonization, transmission, and infection in children. To achieve this, we need to better understand the dynamics and determinants of pediatric nasal microbiota. The overall objective of this proposal is to identify commensals that can competitively exclude S. aureus in the pediatric nasal environment. The central hypothesis, based on our preliminary studies, is that competitive exclusion from non-pathogenic nasal commensals, such as Dolosigranulum, can persistently resist S. aureus colonization. The rationale for the proposed research is that a better understanding of nasal microbiota stability and succession, combined with experimental testing of how Dolosigranulum and other commensals interact with S. aureus will provide important insights into the potential effectiveness of nasal probiotics. The study's hypothesis wil be tested through two specific aims: Aim 1: Determine if children with high absolute abundances of specific nasal commensals have lower risk of carrying S. aureus in the first year of life; and Aim 2: Empirically determine Dolosigranulum's ability to competitively exclude S. aureus in a novel epithelium-microbiome culture model. Aim 1 will be accomplished using an existing collection of longitudinal nasal samples from infants in the first year of life (n = 203). The baseline (i.e., month 1) sample will be characterized by absolute abundance-based microbiome analysis to identify infants with Dolosigranulum- or S. aureus-dominated nasal community state type (CST). The microbial succession of 30 infants with each CST at baseline will be characterized to determine the dynamics of these CSTs. To assess nasal bacterial competition experimentally, Aim 2 will construct an epithelium-microbiome model using samples with select CSTs from Aim 1, which will undergo direct challenges with S. aureus and other nasal CSTs. The approach is innovative, in this team's opinion, because it will construct and validate a novel in vitro model system to recapitulate observed nasal CSTs and enable empiric testing of our competitive-exclusion hypothesis in a mixed culture environment. The proposed research is significant, because it is a proof-of-principle study of nasal probiotics against S. aureus. Importantly, the project will generate an effective model system for future host-microbe and microbe-microbe studies that will accelerate the discovery of new ways to prevent S. aureus colonization and infection.