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）在人鼻咽中的上皮表面定居幼儿期，仍然是呼吸道疾病的重要原因。在全球范围内，SPN导致1500万例每年肺炎球菌疾病（PD），儿童死亡约为050万。 Pd的处理抗菌素耐药性（包括对大环内酯类的耐药性）的出现阻碍了。最多 ERM（B），RNA甲基酶和/或外排/核糖体赋予肺炎球菌耐药性由MEF（E）/MEL介导的保护在大环内酯类排出遗传组装（MEGA）元件上介导的保护。大型与TN916共轭转座相关的元素，但不编码假定的重组酶，已经集成了在肺炎球菌染色体中至少进入四个基因座，I – IV级。分子流行病学研究表现出较高的含有II类大型的分离株的患病率，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被称为集成和结合元素（ICE）已经出现，也有助于散布大环内酯类的耐药性（均为ERMB 和Mega）和其他抗生素抗性标记。同时获得大型和冰编码的抵抗力大概发生在人鼻咽，效率和特定机制期间发生通过将巨型元素和冰散布在鼻咽中的肺炎球菌之间，尚不清楚。我们的人鼻咽生物膜中肺炎球菌单向转化的新发现已有提供了有关肺炎链球菌基因转移的新见解。在此提案中，使用既定模型人鼻咽混凝土生物膜和新表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冰介导。在AIM 1中，我们将评估基因组重组是否热点或应变背景，影响重组频率（RF），并考虑到不同的患病率巨型课。供体应变由四个大型班级中的每一个设计，并定义了肺炎球菌临床将进行包含巨型类别的分离株，以评估基因组基因局和菌株的贡献背景分别。 RF和特定的重组位点都将以重组为单位定义。在 AIM 2我们将研究是否通过转化进行结合或重组，驱动冰的动员编码大花环抗性决定剂。冰分的分子机制使用具有灭活的转座子编码动员的突变体将进一步研究肺炎球菌蛋白质和蛋白质介导能力。确定水平传播机制和两臂大花环耐药性遗传确定剂的频率对于新的干预措施很有价值旨在减少肺炎链球菌抗生素耐药性传播的燃烧。