Molecular basis of decreased susceptibility to beta-lactam antibiotics in Streptococcus pyogenes

描述性标题：儿童对β-内酰胺类抗生素敏感性降低的分子基础 化脓性链球菌 项目摘要/摘要 人类致病菌化脓性链球菌(GAS)引起的细菌超过 全球每年有7亿人感染。β-内酰胺类抗生素是，而且一直是一线药物。 治疗气性咽炎和侵袭性感染。其原因仍然笼罩在神秘和 据推测，这种病原体70年来一直对β-内酰胺类抗生素一致敏感。 然而，最近的一篇论文描述了两种引起气体感染的菌株，它们的数量显著减少 对β-内酰胺类抗生素氨苄西林和阿莫西林的敏感性，引起了美国的高度关注 国家和国际传染病界。这一发现，加上我们最近的发现 对β-内酰胺类抗生素敏感性显著降低的侵袭性气体菌株远远多于 比之前想象的更普遍，地理上也更广泛，已经成为 在此提出的研究。为了实现我们大大加强目前对两国关系的理解的目标 在特定的基因突变和降低气体β-内酰胺敏感性之间，以下两个特定的 提出了目标。具体目标1：测序和分析11,000株菌株的基因组，以确定 青霉素结合蛋白2X(Pbp2x)和青霉素结合蛋白1A的突变谱 (Pbp1A)从咽炎和无症状携带者中提取的GAS基因。我们将确定九个国家的麦克风指数 2750株(25%)菌株上有常用的β-内酰胺类药物。这两个基因的突变是已知的 降低了许多生物体对β-内酰胺类药物的敏感性，包括致病性链球菌。我们将利用我们的 几十年来从全球来源回收的40,000个气体菌株的独特集合。具体目标2： 构建并分析50个等基因突变株以检验特定自然发生的假说 PBP2X和PBP1a中的氨基酸替换降低GAS对β-内酰胺类药物的敏感性 抗菌药物，MIC药敏分析。在这两个目标中提出的研究结果 将提供广泛而独特的数据，以便更全面地了解这一关键新项目的范围 抗菌素耐药性威胁。有理由推测，由此产生的数据最终也可能导致 为预防、限制和治疗耐药气体感染提供新的翻译策略。一个关键的动机 是在很短的时间内产生并提供这种广泛的分子数据，这样它就可以 对研究、医疗和公共卫生社区的最大用处。我们相信大部分拟议中的 研究应该在二十年前就进行了，当时人们意识到我们在 我们对GAS如何形成的知识降低了对β-内酰胺类抗生素的敏感性。最重要的是， 拟议的研究将生成一个可供所有个人挖掘和使用的社区数据资源 从不同的重点领域研究气体感染及耐药性。

DESCRIPTIVE TITLE: Molecular basis of decreased susceptibility to beta-lactam antibiotics in Streptococcus pyogenes PROJECT ABSTRACT/SUMMARY The human bacterial pathogen Streptococcus pyogenes (group A streptococcus, GAS) causes more than 700 million human infections annually worldwide. Beta-lactam antibiotics are, and have been, the first-line treatment for GAS pharyngitis and invasive infections. For reasons that remain shrouded in mystery and speculation, this pathogen has continued to be uniformly susceptible to beta-lactam antibiotics for 70 years. However, a recent paper described two GAS infection-causing strains with significantly decreased susceptibility to the beta-lactam antibiotics ampicillin and amoxicillin, causing great concern in the United States and international infectious disease community. This revelation, coupled with our recent discovery that invasive GAS strains with significantly decreased susceptibility to beta-lactam antibiotics are far more common and geographically widespread than previously thought, have served as the catalyst for the research proposed herein. To achieve our goal of greatly enhancing current understanding of the relationship between specific gene mutations and decreased GAS beta-lactam susceptibility, the following two specific aims are proposed. Specific Aim 1: Sequence and analyze the genomes of >11,000 strains to define the spectrum of mutations present in the penicillin-binding protein 2X (pbp2x) and penicillin-binding protein 1A (pbp1A) genes in GAS recovered from pharyngitis and asymptomatic carriers. We will determine MICs for nine commonly used beta-lactams on 2,750 (25%) of the strains. Mutations in these two genes are known to confer decreased beta-lactam susceptibility in many organisms, including pathogenic streptococci. We will exploit our unique collection of 40,000 GAS strains recovered over decades from global sources. Specific Aim 2: Construct and analyze 50 isogenic mutant strains to test the hypothesis that specific naturally-occurring amino acid replacements in PBP2X and PBP1A decrease the susceptibility of GAS to beta-lactam antibiotics, as judged by MIC susceptibility analysis. The results of the studies proposed in these two aims will provide extensive unique data necessary to more fully understand the scope of this critical new antimicrobial resistance threat. It is reasonable to speculate that the resulting data may also ultimately lead to novel translational strategies to prevent, limit, and treat antibiotic-resistant GAS infections. A key motivation is to generate and make available this extensive molecular data in a very short timeframe so that it can be of the greatest use to the research, medical, and public health communities. We believe much of the proposed research should have been done two decades ago, soon after it was recognized that we had massive gaps in our knowledge about how GAS develops decreased susceptibility to beta-lactam antibiotics. Foremost, the proposed research will generate a community data resource that can be mined and used by all individuals studying GAS infections and antimicrobial resistance from different areas of emphasis.