Macrolide resistance transfer in Streptococcus pyogenes

项目摘要 A组链球菌（GAS）是一种严格的人类病原体，主要感染咽喉或咽喉部的上皮细胞， 皮肤，导致每年约7.5亿例感染。高发病率和死亡率是由侵入性GAS引起的 （iGAS）疾病。尽管其作为全球病原体的重要性，但GAS没有可用的疫苗。在 C.D.C.的2019年抗生素耐药性威胁报告，红霉素耐药GAS被列为“关注 威胁”，并且对红霉素耐药的侵入性GAS（iGAS）分离株的%最近增加了两倍。大环内酯类 通常用于β-内酰胺过敏患者，林可酰胺类药物对iGAS非常有效 疾病，因为外毒素生产停止。气体中的耐腐蚀性问题进一步得到解决。 到2019-2020年，由于青霉素改变而出现稳定的β-内酰胺耐药性的报告， 结合蛋白;抗性基因横向传播到其他GAS菌株的可能性非常高。 这项拟议中的研究旨在更深入地了解这种疾病的生物学原因和临床后果。 通过GAS获得携带大环内酯类耐药基因（R-基因）的移动的遗传元件（MGE）。目的 1试图定义（接近）完整的MGE库的遗传结构，大环内酯类- GAS中的抗性基因。目的2使用R-基因-MGE之间水平转移的实验模型， GAS菌株，以优化微环境条件并产生亲本-受体的同基因对 和新的重组菌株。目的3评估MGE获得对宿主细胞表型的影响， 独立于耐药性;预测几种货物基因改变全局基因表达和/或 有助于致病。将比较同基因对的转录组和适合度。的小鼠模型 iGAS疾病将检验MGE获得导致其内在毒力增加的假设。 新的重组体。如果正确的话，数据可以解释流行病学调查结果的高度关联， iGAS疾病的大环内酯类耐药性，从而为未来的研究提供了一个平台， 机制等 拟从拟议工作中开发的工具包括大环内酯类的综合结构组织- 将张贴在方便用户的互动网站www.pubmlst.org上（目标1），并改进 通过过滤交配进行水平基因转移的实验方案（Aim 2）。除了检验假设 MGE在无寄生虫环境中赋予表型变化，转录组分析（目的3）是 探索性的，并可能提供一个窗口到关键的分子机制。

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.