Impact of Binary Toxin on Recurrent Clostridium difficile Infection

二元毒素对复发性艰难梭菌感染的影响

• 批准号: 9045377
• 负责人: Stuart Brian Johnson
• 金额: --
• 依托单位: EDWARD HINES JR VA HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-01 至 2019-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9045377
• 关键词: ADP ribosylation; Actins; Acute; Adherence; Affect; Animals; Antibiotics; Attention; Canada; Caring; Cecum; Cell Line; Cell Surface Extensions; Characteristics; Clinical; Clostridium difficile; Cytoskeletal Proteins; Data; Detection; Diagnosis; Diarrhea; Elderly; Epidemic; Epidemiology; Epithelial Cells; Feces; Future; Genes; Hamsters; Health; Health care facility; Healthcare; Hospitals; Human; Immunoassay; In Vitro; Infection; Integration Host Factors; Intestines; Investigation; Knock-out; Lead; Length of Stay; Metronidazole; Microtubules; Modeling; North America; Parents; Pathogenesis; Patients; Play; Production; Recurrence; Reporting; Research; Resistance; Risk; Risk Factors; Role; Specimen; Testing; Toxin; Vancomycin; Vesicle; Veterans; Virulence Factors; base; design; improved; in vivo; intestinal epithelium; mutant; novel; pathogen; research study

 DESCRIPTION (provided by applicant): Clostridium difficile infection (CDI) has been an increasingly common and complicated treatment issue for veteran and non-veteran patients over the past decade. One of the most difficult management issues is that of recurrent CDI. ~20% of patients who are successfully treated with either metronidazole or vancomycin will have a recurrent episode. Those who have already had a recurrent episode have ~50% chance of third diarrheal episode and some patients will have recurrent CDI for months or years. In addition, recurrent CDI has had a major impact on healthcare facilities because of frequent readmission rates to acute care facilities. Several host factors have been implicated as risks for recurrent CDI. However, there has been relatively little attention paid to pathogen or bacterial factors that might influence the risk of recurrence. The increase in rates of CDI and complications such as recurrent CDI over the past decade has coincided with the emergence of the epidemic C. difficile BI/027/NAP1 strain. Several potential virulence factors expressed by this strain have been proposed, but recent evidence suggests that binary toxin (CDT) produced by this strain and other clinically important (e.g., BK/078/NAP7) strains may play a critical adjunctive role in CDI pathogenesis. C. difficile binary toxin (CDT) is unrelated to the large, single unit glycosylating toxins, toxin A and B. This 2-component (binary) toxin acts by ADP-ribosylation of the cytoskeletal protein, actin, resulting in microtubular structural changes and epithelial cell membrane protrusions which increase adherence and colonization of C. difficile. Our research aims are designed to test the hypothesis that binary toxin increases the risk of recurrent CDI by two experimental lines of investigation. First, we will use the hamster model of CDI to demonstrate the effect of binary toxin by using isogenic mutants of C. difficile in which the binary gene toxin is knocked out. Second, we will use a newly developed immunoassay for binary toxin to test patient stool specimens and correlate the presence of fecal binary toxin with clinical recurrence of CDI. The specific aims of this proposal include: 1. Establish a reproducible hamster model of CDI recurrence. Aim 1a) Construct binary toxin mutants in the epidemic-associated BI and BK strains (CDTneg) for the baseline experiments in the hamster model Aim 1b) Establish a reproducible recurrence rate in the hamster model using binary toxin mutants (CDTneg) & confirm increased recurrence rates using respective parent (CDTpos) strains 2. Determine the mechanism of increased CDI recurrence due to binary toxin Aim 2a) Determine the mechanism in vitro using a human intestinal epithelial cell line Aim 2b) Determine the mechanism in vivo in hamsters 3. Correlate the expression of binary toxin in patients with CDI recurrence Aim 3a) Correlate fecal binary toxin detection with CDI recurrence Aim 3b) Correlate the presence of binary toxin-positive C. difficile strains with CDI recurrence

 描述（由申请人提供）： 在过去的十年中，艰难梭菌感染（CDI）一直是退伍军人和非退伍军人患者的越来越普遍且复杂的治疗问题。最困难的管理问题之一是经常性CDI。在成功治疗甲硝唑或万古霉素的患者中，约有20％的患者会复发。那些已经经常发作的人有〜50％的腹泻发作的机会约50％，有些患者会经常出现CDI数月或几年。此外，由于经常再入院率对急性护理设施，经常发生的CDI对医疗机构产生了重大影响。已经实施了几种宿主因素作为反复发生CDI的风险。但是，对可能影响复发风险的病原体或细菌因素的关注相对较少。 CDI速率和过去十年中的复发性CDI等并发症的增加与艰难梭菌BI/027/NAP1菌株的出现相吻合。已经提出了该菌株表达的几种潜在病毒因子，但是最近的证据表明，该菌株和其他临床重要重要（例如BK/078/NAP7）菌株产生的二元毒素（CDT）可能在CDI发病机理中起关键的辅助作用。艰难梭菌二进制毒素（CDT）与大型单位单位糖基毒素，毒素A和B无关。这种2-成分（二进制）毒素通过ADP-核糖基化的细胞骨骼蛋白质，肌动蛋白的ADP-核糖化作用，导致微管结构变化和上皮细胞膜片蛋白的侵蚀蛋白，从而增加了肌肉蛋白，从而增加了C. C. C. C. C. C. C.的质量。我们的研究目的旨在检验以下假设：二元毒素通过两种实验研究线增加了复发CDI的风险。首先，我们将使用CDI的仓鼠模型来证明二进制毒素的作用，并使用艰难梭菌的异源性突变体，其中二进制基因毒素被淘汰。其次，我们将使用新开发的免疫测定法进行二元毒素测试患者粪便标本，并将粪便二元毒素的存在与CDI的临床复发相关。该提案的具体目的包括：1。建立CDI复发的可再现仓鼠模型。目的1A）在仓鼠模型目标中的基线实验的流行病相关BI和BK Strifes（CDTNEG）中构建二进制毒素突变体（CDTNEG）AIM 1B）在仓鼠模型中使用二进制毒素突变体（CDTNEG）的仓鼠模型中可重复的复发率（CDTNEG），并确认了使用相对父母的复发率提高的复发率（CDTP）。 toxin Aim 2a) Determine the mechanism in vitro using a human intestinal epithelial cell line Aim 2b) Determine the mechanism in vivo in hamsters 3. Correlate the expression of binary toxin in patients with CDI recurrence Aim 3a) Correlate fecal binary toxin detection with CDI recurrence Aim 3b) Correlate the presence of binary toxin-positive C. difficile strains with CDI recurrence