Genetic Basis of Virulence of Community MRSA Clone USA300

社区 MRSA 克隆 ​​USA300 毒力的遗传基础

• 批准号: 7784570
• 负责人: Henry F HENRY CHAMBERS
• 金额: $ 38.24万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-04-01 至 2012-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7784570
• 关键词: Acquired Immunodeficiency Syndrome; Adherence; Adhesions; Affect; Animal Model; Antibiotic Resistance; Antibiotics; Antibodies; Arginine; Attenuated; Bacteremia; Bacteria; Be++ element; Beryllium; Biological Assay; Cells; Chemotaxis; Code; Communities; Complement Inactivators; Cytolysis; Development; Disease; Drug resistance; Elements; Enterotoxins; Epidemic; Eukaryotic Cell; Exposure to; Gene Cluster; Genes; Genetic; Genomic Islands; Genomics; Genus staphylococcus; Host Defense; Human; Immune; In Vitro; Indium; Infection; Learning; Lung; Measures; Mobile Genetic Elements; Modeling; Monobactams; Mutation; Negative Finding; Organ; Organ Specificity; Oryctolagus cuniculus; Panton-Valentine leukocidin; Parents; Pathogenesis; Pathogenicity Island; Penicillins; Phagocytosis; Pharmaceutical Preparations; Platelet Factor 4; Pneumonia; Prevention approach; Production; Prophages; Protein S; Proteins; Public Health; Research; Resistance; Role; SOS Response; Staphylococcal Infections; Staphylococcus aureus; Staphylococcus aureus auR protein; Superantigens; Testing; Tissues; Toxin; United States; Virulence; Virulence Factors; Virulent; base; beta-Lactam Resistance; in vitro Assay; killings; methicillin resistant Staphylococcus aureus; mutant; neutrophil; novel; novel therapeutic intervention; pathogen; public health relevance; research study; resistant strain

DESCRIPTION (provided by applicant): Staphylococcus aureus is a major human pathogen. It can cause rapidly fatal infections. A highly virulent clone of methicillin resistant S. aureus (MRSA), USA300, is epidemic in communities in the United States. MRSA is resistant to all antibiotics chemically related to penicillin, thus emergence of this clone is a serious public health issue. Our research objective is to identify genes that contribute to virulence of USA300. Emergence of USA300 is associated with acquisition of certain mobile genetic elements, which we suspect carry genes that impact virulence. To test this hypothesis, mutants of USA300 in which suspected virulence genes have been deleted will be tested in rabbit infection models and in vitro assays to determine if their virulence is reduced compared to the normal strain. Polymorphonuclear neutrophils (PMNs) are the first line of innate host defense against S. aureus infection and are critical for bacterial clearance. PMN function will be assayed in vitro to determine whether virulence factors affect human PMN chemotaxis, phagocytosis, or bacterial killing. Specific aims are: 1) To identify virulence determinants in the arginine catabolic mobile element (ACME), which is unique to USA300. Deletion of ACME reduces virulence. Three "likely suspect virulence genes, arcA, opp-3A and opp-3DF, will be deleted and each mutant tested to determine which impact virulence. 2) To determine whether SOS response induced by non-lethal exposure to beta-lactam antibiotic generates adaptive mutations offering a survival advantage to MRSA. 3) To determine if disruption of PVL genes attenuates virulence in a rabbit pneumonia model. PVL (Panton-Valentine leukocidin) is generally assumed to be the most important virulence factor in USA300, but this is highly controversial. The rabbit as a species is sensitive to PVL and lung may be target organ. Results from this model should help resolve the controversy as to whether PVL is a major virulence factor. 4) To determine whether genes within two other elements, (Sa3 prophage and SaPI5 pathogenicity island, encode virulence determinants. Relevance: Emergence of virulent, drug-resistant strains of S. aureus in the community is a public problem second only to AIDS in scope and importance. Defining genes contributing to the special virulence of USA300 strains is a critical first step for developing new drugs and approaches for treatment of severe infections caused by community-associated MRSA strains. PUBLIC HEALTH RELEVANCE Antibiotic resistant strains of Staphylococcus aureus, an important human pathogen, are on the rise. One particular clone, USA300, seems to be especially virulent. Several genes that could be important for virulence are uniquely present in USA300. By knocking each of these genes out and testing for loss of virulence, we hope to learn which genes code for virulence. Once these genes are identified, strategies to block their effects may be developed.

描述（由申请人提供）：金黄色葡萄球菌是主要的人类病原体。它可能引起迅速致命的感染。在美国社区中，美国300的高度毒性克隆是甲氧西林金黄色葡萄球菌（MRSA），美国300的流行病。 MRSA对与青霉素化学相关的所有抗生素具有抗药性，因此该克隆的出现是一个严重的公共卫生问题。我们的研究目标是确定导致USA300毒力的基因。 USA300的出现与获得某些移动遗传元件的获取有关，我们怀疑这些遗传元素具有影响毒力的基因。为了检验该假设，将在兔子感染模型和体外测定中测试可疑毒力基因的USA300突变体，以确定与正常菌株相比，其毒力是否降低。多形核中性粒细胞（PMN）是针对金黄色葡萄球菌感染的先天宿主防御的第一线，对于细菌清除至关重要。 PMN功能将在体外测定，以确定毒力因子是否影响人类PMN趋化性，吞噬作用或细菌杀伤。具体目的是：1）确定在USA300所独有的精氨酸分解代谢移动元件（ACME）中的毒力决定因素。 ACME的缺失降低了毒力。将删除三个“可能可疑的毒力基因，ARCA，OPP-3A和OPP-3DF，并测试每个突变体，以确定哪种影响毒力。2）确定是否通过非致命暴露于β-内酰胺抗生素抗生素产生的适应性突变对MRSA的生存优势来确定bbeta-lactam抗生素产生的SOS响应是否会导致MRSA。 PVL（Panton-valentine Leukocidin）通常被认为是USA300的最重要的毒力因素，但这是高度争议的。 SAPI5的致病性岛，编码毒力决定因素：在社区中抗药性的抗药性菌株的出现仅是为范围和重要性而造成新药物的特殊治疗率的范围的范围和重要性抗生素的抗生素是一种重要的人类病原体，一种特定的克隆，USA300。

项目成果

Community-associated meticillin-resistant Staphylococcus aureus.

• DOI: 10.1016/s0140-6736(09)61999-1
• 发表时间: 2010-05-01
• 期刊: LANCET
• 影响因子: 168.9
• 作者: DeLeo, Frank R.;Otto, Michael;Kreiswirth, Barry N.;Chambers, Henry F.
• 通讯作者: Chambers, Henry F.

Subinhibitory fluoroquinolone exposure selects for reduced beta-lactam susceptibility in methicillin-resistant Staphylococcus aureus and alterations in the SOS-mediated response.

• DOI: 10.1016/j.resmic.2009.03.003
• 发表时间: 2009-04
• 期刊: Research in microbiology
• 影响因子: 2.6
• 作者: P. Tattevin;Li Basuino;H. Chambers

Global changes in Staphylococcus aureus gene expression in human blood.

• DOI: 10.1371/journal.pone.0018617
• 发表时间: 2011-04-15
• 期刊: PloS one
• 影响因子: 3.7
• 作者: Malachowa N;Whitney AR;Kobayashi SD;Sturdevant DE;Kennedy AD;Braughton KR;Shabb DW;Diep BA;Chambers HF;Otto M;DeLeo FR
• 通讯作者: DeLeo FR