Candida Pathogenesis in Surgery and Trauma

外科和创伤中的念珠菌发病机制

基本信息

批准号：
7149174
负责人：
Carol L Wells
金额：
$ 29.92万
依托单位：
UNIVERSITY OF MINNESOTA
依托单位国家：
美国
项目类别：
财政年份：
1999
资助国家：
美国
起止时间：
1999-06-01 至 2008-11-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7149174
关键词：
Accounting Adherence Agar Antibiotics Antifungal Therapy Biological Assay Blood Candida Candida albicans Candidiasis Cell Wall Cells Condition Data Defect Dexamethasone Diagnosis Disseminated candidiasis Dyes Elements Enterocytes Enzyme-Linked Immunosorbent Assay Epithelial Filament Fluorochrome Funding Gastrointestinal tract structure Gene Mutation Germ Human Hyphae Hypoxia Immunocompromised Host In Vitro Indium Infection Intensive Care Units Intestines Intuition Knowledge Lipopolysaccharides Liquid substance Modality Mus Mutation Operative Surgical Procedures Pathogenesis Patients Penetration Peptidoglycan Phase Play Predisposition Progress Reports Relative (related person)Research Personnel Risk Role Saccharomycetales Serum Stream System Systemic infection Testing Therapeutic Trauma Tube Vagina Virulence WNT1 gene Work Yeasts base design fungus in vivo intestinal epithelium member mortality mouse model mutant prophylactic research study

项目摘要

Candida species are the fourth most common cause of nosocomial blood stream infections, and C. albicans accounts for 50% to 75% of Candida species in essentially all studies. Despite appropriate antifungal therapy, mortality is 35% to 75%. Patients at highest risk include immunosuppressed patients, trauma patients, and postsurgical patients, and a large proportion of cases occur in intensive care units. C. albicans undergoes reversible morphologic switching, producing budding yeast and filamentous forms that include germ tubes, pseudohyphae and true hyphae. Many investigators have assumed that filamentous forms are responsible for epithelial invasion. However, recent data from mouse models of extraintestinal dissemination indicate that the yeast cell, rather than filamentous forms, might be more important in C. albicans penetration of intestinal epithelium. Our working hypothesis is that yeast cells play a key role in interactions (adherence and penetration) of this fungus with the intestinal epithelium. The general approach is to use wild type and well-characterized C. albicans mutant strains (with defects in morphologic switching) to challenge this hypothesis in vitro (cultured enterocytes) and in vivo (mouse models). Because C. glabrata has recently emerged as the second most frequent cause of candidiasis, and because C. glabrata is the only species (of the more than 80 recognized Candida species) that does not form filaments and exists only in the yeast form, experiments also focus on C. glabrata. In vitro experiments are designed to separately characterize the interactions (adherence, internalization, intracellular survival) of yeast and filamentous forms with cultured enterocytes, and assay systems include ELISA and a double fluorochrome assay using calcoflour and the vital dye FUN-1. Mouse models include antibiotic-induced intestinal Candida colonization, ligated intestinal loops, and the Stamper-Woodruff assay. The effect of bacterial cell wall products (lipopolysaccharide and peptidoglycan), dexamethasone, and hypoxia on extraintestinal dissemination of Candida is also clarified. If our hypothesis is validated (that the yeast cell is of primary importance in extraintestinal dissemination), then efforts to design more effective in vitro susceptibility assays, as well as more effective prophylactic and therapeutic modalities, might more reliably target yeast rather than hyphal elements. Such knowledge should accelerate our ability to diagnose, treat, and control systemic candidiasis.

念珠菌物种是医院血流感染的第四大原因，在所有研究本质上，白色念珠菌占念珠菌物种的50％至75％。尽管有适当的抗真菌疗法，但死亡率为35％至75％。风险最高的患者包括免疫抑制的患者，创伤患者和外科治疗患者，并且在重症监护病房中发生了很大比例的病例。白色念珠菌经历可逆的形态转换，产生萌芽的酵母和丝状形式，其中包括细菌管，假氢和真菌丝。许多研究人员认为丝状形式是造成上皮入侵的原因。然而，来自肠外传播小鼠模型的最新数据表明，在白色念珠菌渗透肠上皮细胞中，酵母细胞而不是丝状形式可能更重要。我们的工作假设是，酵母细胞在这种真菌与肠上皮的相互作用（粘附和穿透）中起关键作用。一般的方法是使用野生型和特征良好的白色念珠菌突变菌株（形态切换中的缺陷）在体外（培养的肠上皮细胞）和体内（小鼠模型）挑战这一假设。由于Glabrata C. Glabrata最近成为念珠菌病的第二常见原因，并且由于Glabrata是唯一的（80多种公认的念珠菌物种），不形成细丝，并且仅以酵母菌形式存在，因此实验还集中在C. glabrata上。设计的体外实验旨在分别表征酵母和具有培养的肠上皮细胞的丝状形式的相互作用（粘附，内部化，细胞内存活率），并且测定系统包括ELISA和使用Calcoflour和Vital Dye Fun-1的双荧光色素测定法。小鼠模型包括抗生素诱导的肠道念珠菌定植，结扎的肠环和Stamper-Woodruff分析。还阐明了细菌细胞壁产物（脂多糖和肽聚糖），地塞米松和缺氧对念珠菌外肠外传播的影响。如果我们的假设得到了验证（酵母细胞在肠外传播中至关重要），那么设计更有效的体外敏感性测定法，以及更有效的预防性和治疗方式，可能会更可靠地靶向酵母，而不是菌丝元素。这种知识应该加快我们诊断，治疗和控制全身念珠菌病的能力。