Macrolide resistance transfer in Streptococcus pyogenes

项目总结 A组链球菌(GAS)是一种严格的人类病原体，主要感染喉部或 皮肤，导致每年约7.5亿人感染。侵入性气体导致的高发病率和死亡率 (IGAS)病。尽管它作为一种全球病原体很重要，但目前还没有针对GAS的疫苗。在 疾控中心《S 2019年抗生素耐药性威胁报告》红霉素耐药气体被列为关注对象 而对红霉素耐药的侵袭性气体(IGAS)菌株的比例最近增加了两倍。大环内酯类化合物 通常用于β-内酰胺过敏的患者，林可胺对IGAS非常有效 疾病是因为外毒素的产生停止了。气体中的抗生素耐药性问题进一步 再加上2019-2020年的报告称，由于青霉素的改变，出现了稳定的β-内酰胺类耐药性- 结合蛋白；耐药基因向其他气体菌株横向传播的可能性非常高。 这项拟议的研究旨在更深入地了解脑出血的生物学原因和临床后果。 用GAS获得含有大环内酯类抗药性基因(R-基因)的移动遗传元件(MGES)。目标 1试图定义含有大环内酯类化合物的(接近)完整的MGES的遗传结构。 GAS中的抗性基因。目的2利用R基因-MGES水平转移的实验模型 气体菌株，以优化微环境条件并产生同基因的亲本-受体对 和新的重组菌株。目的3评估获得MGE对宿主细胞表型的影响 与耐药性无关；几个Cargo基因被预测会改变全球基因表达和/或 对致命性有贡献。将比较同基因对的转录本和适合度。一种小鼠模型 IGAS病将检验这样一种假设，即获得MGE会导致该病毒内在毒力的增加 新的重组。如果是正确的，数据可以解释流行病学研究发现的高度相关性。 大环内酯类抗药性与IGAS病，从而为未来的研究提供了一个探索分子的平台 机械装置。 拟开展的工作将开发的工具包括大环内酯的综合结构组织-- 抗性MGES，将张贴在交互式用户友好网站www.pubmlst.org(Aim 1)上，并已改进 过滤交配水平基因转移的实验方案(目标2)。除了检验假设之外 MGES在不含抗生素的环境中传递表型变化，转录组分析(目标3)是 探索性的，并可能提供一个了解关键分子机制的窗口。

PROJECT SUMMARY Group A Streptococcus (GAS) is a strict human pathogen that primarily infects the epithelia at the throat or skin, leading to ~750 million infections per year. High rates of morbidity and mortality result from invasive GAS (iGAS) disease. Despite its importance as a global pathogen, there is no vaccine available for GAS. In the C.D.C.'s Antibiotic Resistance Threats Report of 2019, erythromycin-resistant GAS are listed as a “concerning threat” and the % of invasive GAS (iGAS) isolates resistant to erythromycin has recently tripled. Macrolides are commonly prescribed for patients with β-lactam allergies, and lincosamides are highly effective against iGAS disease because exotoxin production is halted. The problem of antibiotic-resistance in GAS is further compounded by 2019-2020 reports on the emergence of stable β-lactam resistance due to altered penicillin- binding proteins; the potential for lateral spread of resistance genes to other GAS strains is very high. The proposed study seeks a deeper understanding of the biological causes and clinical consequences of the acquisition by GAS of mobile genetic elements (MGEs) harboring macrolide-resistance genes (R-genes). Aim 1 seeks to define the genetic architecture of the (near) complete repertoire of MGEs that harbor macrolide- resistance genes in GAS. Aim 2 uses experimental models of horizontal transfer of R-gene-MGEs between GAS strains, to optimize microenvironmental conditions and to generate isogenic pairs of parental-recipient and new recombinant strains. Aim 3 evaluates the effect of MGE acquisition on host cell phenotypes that are independent of drug-resistance; several cargo genes are predicted to alter global gene expression and/or contribute to virulence. Transcriptomes and fitness will be compared for the isogenic pairs. A mouse model for iGAS disease will test the hypothesis that MGE acquisition leads to an increase in the intrinsic virulence of the new recombinant. If correct, data may explain the epidemiological findings on the high association of macrolide-resistance with iGAS disease and thereby, provide a platform for future studies that probe molecular mechanisms. Tools to be developed from the proposed work include a consolidated structural organization for the macrolide- resistance MGEs, to be posted on the interactive user-friendly www.pubmlst.org website (Aim 1), and improved experimental protocols for horizontal gene transfer by filter-mating (Aim 2). In addition to testing the hypothesis that MGEs impart phenotypic changes in an antibiotic-free environment, transcriptome analysis (Aim 3) is exploratory and may provide a window into critical molecular mechanisms.