Antibiotic pressure and selection of TCA cycle mutants in Staphylococcus epidermi

表皮葡萄球菌抗生素压力和TCA循环突变体的选择

• 批准号: 7835649
• 负责人: PAUL D FEY
• 金额: $ 21.89万
• 依托单位: UNIVERSITY OF NEBRASKA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-05-08 至 2011-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7835649
• 关键词: Acetates; Aconitate Hydratase; Anti-Bacterial Agents; Antibiotic Therapy; Antibiotics; Bacteria; Bacterial Drug Resistance; Bacterial Infections; Biological Assay; Cavia; Cell Death; Ciprofloxacin; Citric Acid Cycle; Clinical; Clinical Microbiology; Complement; Daptomycin; Data; Electron Transport; Environment; Enzymes; Escherichia coli; Exposure to; Fluorescein; Fluoresceins; Fumarate Hydratase; Generations; Genetic; Genus staphylococcus; Growth; Hydroxyl Radical; Infection; Ions; Iron; Isocitrate Dehydrogenase; Laboratories; Mediating; Medical center; Metabolic Pathway; Methicillin Resistance; Microbial Biofilms; Modeling; Mutation; NADH; Nebraska; Oxacillin; Pathway interactions; Phenolsulfonphthalein; Phenotype; Physiological Adaptation; Population; Production; Reaction; Reporting; Resistance; Staphylococcus aureus; Staphylococcus epidermidis; Sulfur; Superoxides; Testing; Time; Tissue Cage; Universities; Vancomycin; bacterial resistance; bactericide; clinical efficacy; clinically relevant; design; gene replacement; killings; knockout gene; mutant; novel; pressure; prevent; public health relevance; research study; resistance factors

DESCRIPTION (provided by applicant): A recent report by Kohanski et al. demonstrated that multiple classes of bactericidal antibiotics stimulate the production of hydroxyl radicals thus accelerating bacterial cell death in Escherichia coli. Although different classes of antibiotics have unique mechanisms of action, their data suggest that they mediate killing through a common pathway involving hydroxyl radicals. By an unknown mechanism, bactericidal antibiotics transiently increase the reduction of NAD+ via the TCA cycle, increasing superoxide generation in the ETC. Superoxide damages iron-sulfur clusters; the released ferrous ion is thus available for the Fenton reaction generating hydroxyl radicals. Validating these studies, allelic replacement gene knockouts of the TCA cycle enzymes aconitase (acnB) and isocitrate dehydrogenase (icdA) abrogated the killing effect of bactericidal antibiotics. In addition, bactericidal antibiotics did not induce hydroxyl radical formation in the TCA cycle mutants. Data presented in this application demonstrate that 26% of clinical Staphylococcus epidermidis isolates are TCA cycle defective. In addition, oxacillin time-kill studies against a S. epidermidis 1457 aconitase mutant (1457 acnA::tetM) revealed that killing was decreased 2.6 log10 compared to wild type. Therefore, the loss of TCA cycle activity represents a physiological adaptation of the bacterium to an environment where antibiotic pressure is prevalent. The central hypothesis of this application is that antibiotic pressure selects for TCA cycle mutants within the S. epidermidis population. This hypothesis will be tested by first determining if bactericidal antibiotics induce hydroxyl radical formation in S. epidermidis. Secondly, we will determine the percentage of clinically relevant S. epidermidis isolates that are defective in TCA cycle function. Lastly, we will determine if TCA cycle mutants are more recalcitrant to antibiotic therapy using a guinea pig tissue cage model. This proposal will yield significant new information regarding the physiological adaptation of bacteria allowing growth under antibiotic pressure. Novel means to prevent and treat bacterial infections may be suggested as a result of these studies. PUBLIC HEALTH RELEVANCE: Experiments proposed in this application are designed to determine whether the use of certain antibiotics selects for bacteria that are resistant because of mutations in a common metabolic pathway.

描述（由申请人提供）：Kohanski 等人最近的报告。证明多种杀菌抗生素会刺激羟基自由基的产生，从而加速大肠杆菌中的细菌细胞死亡。尽管不同类别的抗生素具有独特的作用机制，但它们的数据表明它们通过涉及羟基自由基的共同途径介导杀伤作用。通过未知的机制，杀菌抗生素会通过 TCA 循环暂时增加 NAD+ 的减少，从而增加 ETC 中超氧化物的生成。超氧化物会破坏铁硫簇；因此，释放的亚铁离子可用于芬顿反应，产生羟基自由基。验证这些研究后，TCA 循环酶乌头酸酶 (acnB) 和异柠檬酸脱氢酶 (icdA) 的等位基因替换基因敲除消除了杀菌抗生素的杀灭作用。此外，杀菌抗生素不会诱导TCA循环突变体中羟基自由基的形成。本申请中提供的数据表明，26% 的临床表皮葡萄球菌分离株存在 TCA 循环缺陷。此外，针对表皮葡萄球菌 1457 乌头酸酶突变体 (1457 acnA::tetM) 的苯唑西林时间杀灭研究表明，与野生型相比，杀灭率降低了 2.6 log10。因此，TCA循环活性的丧失代表了细菌对抗生素压力普遍存在的环境的生理适应。该应用的中心假设是抗生素压力选择表皮葡萄球菌群体内的TCA循环突变体。该假设将通过首先确定杀菌抗生素是否诱导表皮葡萄球菌中羟自由基的形成来检验。其次，我们将确定 TCA 循环功能缺陷的临床相关表皮葡萄球菌分离株的百分比。最后，我们将使用豚鼠组织笼模型确定 TCA 循环突变体是否更难耐受抗生素治疗。该提案将产生有关细菌在抗生素压力下生长的生理适应的重要新信息。这些研究的结果可能会提出预防和治疗细菌感染的新方法。公共健康相关性：本申请中提出的实验旨在确定某些抗生素的使用是否会选择由于常见代谢途径突变而产生耐药性的细菌。