Detection of Host Response In Clostridium Difficile Infection

 描述(由申请人提供)：这项研究申请的目的是为一种全球重要但诊断较差的与医疗保健相关的传染病，即艰难梭菌感染(CDI)，开发一种诊断测试的范式转变。CDI是由艰难梭菌感染肠道引起的，艰难梭菌是一种革兰氏阳性、芽胞形成、专性厌氧细菌。它可以引起从中度腹泻到严重结肠炎(毒性)的(腹泻)疾病 巨结肠)有很高的死亡风险。在过去的二十年里，CDI重新出现在医疗机构中，死亡率增加了近10倍，医疗保健成本大幅增加。目前的CDI诊断仅限于结合临床症状检测微生物和/或其毒素产物(S)I，不能将感染与单纯定植的患者区分开来，从而导致诊断不准确以及抗生素的误用/过度使用。为了克服这些限制并解决CDI诊断的不确定性，将在本研究项目期间开发和评估CDI诊断的开创性概念。该项目的基本原理是艰难梭菌毒素B的作用机制通过释放非肌肉原肌球蛋白(TM)导致结肠上皮细胞的细胞骨架破坏。我们的假设是，患者粪便中TM的水平升高，这是结肠上皮细胞骨架中的一种主要蛋白质，表明一种特定的 宿主对CDI的反应，可作为艰难梭菌活动性感染的诊断靶标。应用目的是开发和评估粪便标本中TM的检测作为CDI临床显著表现的生物标志物。为了实现这一目标，我们将追求两个具体目标：1)确定临床适用的粪便TM检测的可行性。这一目标将通过执行多项任务来实现--产生TM特异性抗体，优化从粪便标本中回收TM的方法，利用模拟CDI阴性和阳性标本的对照制定和优化TM检测方案，以及测试潜在的干扰。2)评价粪便TM作为CDI特异性宿主反应标志物在临床不同患者群体中的应用。为此，CDI阳性和阴性的临床标本将被用于TM检测，并将数据与相同标本的临床和微生物学记录进行比较。这些记录是通过查阅和使用临床微生物学实验室的残留样本而获得的。CDI诊断的特异性将在由其他肠道细菌病原体(大肠杆菌、沙门氏菌、志贺氏菌和弯曲杆菌)、寄生虫、抗生素相关性腹泻(非感染)和炎症性肠病等肠道疾病引起的腹泻患者的粪便样本上得到验证。这一提出的概念具有巨大的潜力，可以开发一种新的CDI诊断应用程序。这将为下一代传染病诊断测量宿主反应而不是检测病原体或其产物提供范例。我们的长期目标是通过提供宿主反应CDI测试来改善患者护理，该测试可与行业合作伙伴(如TechLab(R)，Inc.)一起开发，作为一种可以通过FDA批准试验的商业测试。

 DESCRIPTION (provided by applicant): The aim of this research application is to develop a paradigm shift in diagnostic testing for a globally important, yet poorly diagnosed, healthcare-associated infectious disease, namely Clostridium difficile infection (CDI). CDI results from infection of the bowel by C. difficile, a Gram-positive, spore-forming, obligate anaerobic bacterium. It can cause (diarrheal) illness ranging from moderate diarrhea to severe colitis (toxic megacolon) with a high risk of death. For the last two decades CDI has re-emerged in healthcare facilities with nearly a 10- fold increase in mortality and significant excess healthcar cost. Current CDI diagnostics is limited to detection of the organism and/or its toxin product(s) i conjunction with clinical symptoms, and does not differentiate infected from simply colonized patients, thus leading to inaccurate diagnosis as well as antibiotic mis/overuse. To overcome these limitations and resolve uncertainty of CDI diagnosis, a ground-breaking concept for CDI diagnosis will be developed and evaluated during this research project. The project rationale is that C. difficile toxin B mechanism of action causes cytoskeletal disruption of colonic epithelial cells with release of non- muscle tropomyosin (Tm). Our hypothesis is that increased levels of Tm, a major protein in colonic epithelial cytoskeleton, in the patient's stool indicates a specific host response to CDI and can be used as a diagnostic target signifying active infection from C. difficile. The application objective is to develop and evaluate Tm detection in stool specimens as a biomarker for clinically significant manifestations of CDI. To accomplish it, we will pursue two specific aims: 1) Determine the feasibility of clinically appropriate fecal Tm detection. This aim will be accomplished by performing multiple tasks - generation of Tm specific antibodies, optimization of Tm recovery method from stool specimens, Tm detection protocol development and optimization utilizing controls mimicking CDI negative and positive specimens, and testing for potential interferences. 2) Evaluate fecal Tm as a CDI specific host response marker on specimens obtained from clinically diverse patient populations. For that, CDI positive and negative clinical specimens will be utilized for Tm detection and data comparison to clinical and microbiological records of the same specimens. The records are available due to access and use of remnant samples from the clinical microbiology laboratory. The specificity of CDI diagnostics will be validated on stool specimens from patients with diarrhea due to other enteric bacterial pathogens (E. coli, Salmonella, Shigella spp, and Campylobacter), parasites, antibiotic-associated diarrhea (not due to infection), and bowel disorders like inflammatory bowel disease. This proposed concept has great potential to allow development of a novel diagnostic application for CDI. It will serve as an example for the next generation of infectious disease diagnostics measuring host response instead of detecting pathogens or their products. Our long term goal is to improve patient care by delivering a host response CDI test ready for development with an industry partner, such as TechLab(r), Inc., as a commercial assay that can undergo FDA clearance trials.