权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

DISSEMINATION OF MACROLIDE RESISTANCE ELEMENTS IN STREPTOCOCCUS PNEUMONIAE

肺炎链球菌中大环内酯类耐药元件的传播

基本信息

批准号：
9888324
负责人：
DAVID S STEPHENS
金额：
$ 16.41万
依托单位：
UNIVERSITY OF MISSISSIPPI MED CTR
依托单位国家：
美国
项目类别：
财政年份：
2019
资助国家：
美国
起止时间：
2019-03-06 至 2022-02-28
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9888324
关键词：
Address Antibiotic Resistance Antibiotics Centers for Disease Control and Prevention (U.S.)Cessation of life Child Chromosomes Clinical Clonal Expansion Competence Complex DNA DNA Transposons Data Elements Engineering Environment Epidemiology Epithelial Epithelium Frequencies Gene Transfer Genetic Genetic Determinism Genetic Recombination Genome Genomics High Prevalence Hot Spot Human Individual Intervention Investigation Macrolide-resistance Macrolides Mediating Microbial Biofilms Mobile Genetic Elements Molecular Movement Multi-Drug Resistance Nasopharynx Nature Pneumococcal Infections Population Prevalence Proteins Recombinants Resistance Ribosomes Serotyping Site Source Streptococcus pneumoniae Surface Virulent World Health Organization clinically relevant design early childhood emerging antimicrobial resistance epidemiology study genomic locus human model insight mutant novel pathogen pressure priority pathogen recombinase respiratory tRNA Methyltransferases

项目摘要

Abstract Streptococcus pneumoniae (Spn) colonizes the epithelial surface of the human nasopharynx in early childhood and remains a significant cause of respiratory illness. Globally, Spn causes 15 million cases of pneumococcal disease (PD) each year leading to approximately ∼0.5 million deaths in children. Treatment of PD has been hindered by emergence of antimicrobial resistance, including the resistance to macrolides. Most pneumococcal macrolide resistance is conferred by Erm(B), the RNA methylase, and/or efflux/ribosomal protection mediated by Mef(E)/Mel on the macrolide efflux genetic assembly (Mega) element. The Mega element, related to Tn916 conjugative transposons but does not encode putative recombinases, has integrated into at least four loci in the pneumococcal chromosome, Mega classes I–IV. Molecular epidemiological studies demonstrated a higher prevalence of isolates containing the class II Mega, which is not caused by clonal expansion. Moreover, a wide array of complex Tn916 related mobile genetic elements, termed integrative and conjugative elements (ICEs), has emerged that also facilitate dissemination of macrolide resistance (both ermB and Mega) and additional antibiotic resistance markers. While acquisition of Mega and ICE-encoded resistance presumably occurs during colonization of the human nasopharynx, the efficiency and the specific mechanisms by which Mega elements and ICEs spread among pneumococci in the nasopharynx is not well understood. Our novel discovery of pneumococcal unidirectional transformation in the human nasopharyngeal biofilms has provided new insights on gene transfer in S. pneumoniae. In this proposal, using an established model of human nasopharyngeal consortial biofilms and the newly characterized uni-directional gene transfer phenomenon, we will determine the mechanisms and frequencies of macrolide resistance dissemination mediated by the Mega elements and ICEs. In Aim 1 we will evaluate whether genomic recombination hot spots or strain background, influence the recombination frequency (rF) and account for different prevalence among Mega classes. Donor strains engineered with each of the four Mega classes and defined pneumococcal clinical isolates containing the Mega classes will be conducted to assess the contribution of genomic loci and strain backgrounds, respectively. Both the rF and the specific recombination sites will be defined in recombinants. In aim 2 we will investigate whether conjugation or recombination via transformation, drives the mobilization of ICE- encoded macrolide resistant determinants. The molecular mechanism of ICE-dissemination among pneumococci will be further investigated using mutants with inactivated transposon-encoded mobilization proteins and proteins mediating competence. Identifying the horizontal dissemination mechanisms and frequencies of the two-major macrolide resistance genetic determinants will be valuable for new interventions aimed at decreasing the burden of antibiotic resistance dissemination in S. pneumoniae.

抽象的肺炎链球菌 (Spn) 定植于人鼻咽部的上皮表面幼儿期仍然是呼吸系统疾病的一个重要原因。在全球范围内，Spn 导致 1500 万例病例肺炎球菌疾病 (PD) 每年导致大约 50 万名儿童死亡。帕金森病的治疗抗生素耐药性的出现阻碍了这一进程，包括对大环内酯类药物的耐药性。最多肺炎球菌大环内酯类耐药性是由 Erm(B)、RNA 甲基化酶和/或外排/核糖体赋予的 Mef(E)/Mel 对大环内酯外排基因组装 (Mega) 元件的保护作用。巨型与 Tn916 接合转座子相关但不编码假定的重组酶的元件已整合进入肺炎球菌染色体中的至少四个基因座，Mega I-IV 类。分子流行病学研究证明含有 II 类 Mega 的分离株的流行率较高，这不是由克隆引起的扩张。此外，一系列复杂的 Tn916 相关的移动遗传元件，称为整合和共轭元件（ICE）的出现也促进了大环内酯类药物耐药性的传播（ermB 和 Mega）和其他抗生素抗性标记。同时收购Mega和ICE编码电阻推测是在人鼻咽定植过程中发生的，其效率和具体机制巨元素和 ICE 在鼻咽部肺炎球菌中传播的方式尚不清楚。我们的人类鼻咽生物膜中肺炎球菌单向转化的新发现为肺炎链球菌基因转移提供了新的见解。在本提案中，使用已建立的模型人鼻咽联合生物膜和新特征的单向基因转移现象，我们将确定大环内酯类耐药性传播的机制和频率由巨型元素和 ICE 介导。在目标 1 中，我们将评估基因组重组热点是否存在或菌株背景，影响重组频率（rF）并解释不同流行率大型课程。供体菌株采用四种 Mega 类别和定义的肺炎球菌临床设计将进行包含 Mega 类的分离株以评估基因组位点和菌株的贡献分别为背景。 rF 和特定重组位点都将在重组体中定义。在目标 2 我们将研究通过转化进行的缀合或重组是否会驱动 ICE-的动员编码大环内酯类耐药决定簇。 ICE传播的分子机制将使用具有失活转座子编码动员的突变体进一步研究肺炎球菌蛋白质和蛋白质介导能力。确定横向传播机制和两种主要大环内酯类耐药遗传决定因素的频率对于新的干预措施将很有价值旨在减轻肺炎链球菌抗生素耐药性传播的负担。