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A tripartite strategy for controlling Clostridioides difficile

控制艰难梭菌的三方策略

基本信息

批准号：
MR/X012190/1
负责人：
Shan Goh
金额：
$ 15.17万
依托单位：
University of Hertfordshire
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2022
资助国家：
英国
起止时间：
2022 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=MR%2FX012190%2F1
关键词：
tripartite strategy controlling Clostridioides difficile

项目摘要

Gut bacteria can exchange DNA in many ways to resist antibiotics and cause untreatable infections. Our research on understanding how and when antibiotic resistance genes (ARGs) are exchanged with other bacteria, and finding new treatment agents should ultimately reduce these occurrences and make infections more easily treated. This research is focused on Clostridioides difficile, an important human pathogen that causes infection with high illness and death rates. C. difficile found in animals and the environment are capable of causing human disease. Antibiotic therapy that disrupts the balance of microbes in the gut is a major risk factor for C. difficile infection (CDI), hence antibiotic treatment of CDI often fails. Also C. difficile is constantly evolving to be antibiotic-resistant because of gene exchange events that involve contact with other cells, bacterial viruses (known as phages), and external DNA such as transposons. Some of these events occur more frequently than others probably because of environmental factors, and understanding these is important for controlling ARG exchange events. For this, we examine C. difficile cells in contact with other bacteria, phages, and external DNA under different environmental conditions that mimic gut conditions such as presence of antibiotics and changing pH, and measure differences in ARG being exchanged between cells. We are investigating new agents that kill or enhance antibiotic-killing of C. difficile as possible treatments for infection. Two such agents we investigate are phages and cationic peptides. Phages are natural enemies of bacteria, and many phages found so far can be genetically altered to efficiently kill C. difficile. We do this by removing phage genes that prevent efficient killing of bacteria, forcing the phage to replicate and break apart its bacterial host cell after infection. Cationic peptides are short pieces of positively-charged proteins that disrupt the cell wall or DNA of bacteria. In this research we will be testing a synthetic cationic peptide for its ability to enhance the activity of antibiotics against C. difficile by mixing them together and adding them to actively growing cells. We also look for agents that protect patients from recurrent CDI, which is a serious problem in about 20% of CDI patients. Probiotics are harmless bacteria that help our gut resist colonisation by pathogens. We are testing the ability of different types of probiotics to stop C. difficile from colonising a human gut model that mimics the natural microbial environment in humans suffering from CDI. This is done by growing bacteria from faecal samples of healthy humans in three flasks of pH, nutrient, and oxygen-free conditions similar to a human large intestine. Antibiotics and C. difficile are then added to the flasks to establish "infection", more antibiotics are added to remove C. difficile and simulate a recurring infection. Probiotics are then added to the system and checked to see if the probiotic prevents C. difficile. We also investigate the ability of harmless C. difficile (which lack the ability to produce toxins) to compete with toxin-producing C. difficile strains and prevent infection. So far we have found a harmless strain that prevents growth and toxin production by a superbug strain of C. difficile under a wide range of experimental conditions and this has not been shown before. This three-pronged approach to control C. difficile in acquiring ARG, growth, and re-colonisation will open new avenues for developing treatments for CDI.

肠道细菌可以通过多种方式交换DNA来抵抗抗生素并导致无法治疗的感染。我们的研究旨在了解抗生素抗性基因（ARG）如何以及何时与其他细菌交换，并寻找新的治疗药物，最终应该减少这些情况的发生，并使感染更容易治疗。这项研究的重点是艰难梭菌，这是一种重要的人类病原体，会导致高患病率和死亡率的感染。动物和环境中发现的艰难梭菌能够引起人类疾病。破坏肠道微生物平衡的抗生素治疗是艰难梭菌感染 (CDI) 的主要危险因素，因此 CDI 的抗生素治疗经常失败。此外，由于涉及与其他细胞、细菌病毒（称为噬菌体）和外部 DNA（例如转座子）接触的基因交换事件，艰难梭菌不断进化为抗生素耐药性。其中一些事件比其他事件发生得更频繁，可能是由于环境因素，了解这些事件对于控制 ARG 交换事件非常重要。为此，我们在模拟肠道条件（例如抗生素的存在和 pH 值变化）的不同环境条件下检查艰难梭菌细胞与其他细菌、噬菌体和外部 DNA 的接触，并测量细胞之间交换的 ARG 的差异。我们正在研究杀死或增强抗生素杀死艰难梭菌的新药物，作为感染的可能治疗方法。我们研究的两种这样的试剂是噬菌体和阳离子肽。噬菌体是细菌的天敌，迄今为止发现的许多噬菌体都可以通过基因改造来有效杀死艰难梭菌。我们通过去除阻碍有效杀死细菌的噬菌体基因，迫使噬菌体在感染后复制并分解其细菌宿主细胞来做到这一点。阳离子肽是带正电荷的蛋白质短片段，可破坏细菌的细胞壁或 DNA。在这项研究中，我们将测试一种合成阳离子肽，通过将它们混合在一起并将其添加到活跃生长的细胞中，来测试其增强抗生素对抗艰难梭菌活性的能力。我们还寻找能够保护患者免受 CDI 复发的药物，这是约 20% 的 CDI 患者面临的严重问题。益生菌是无害的细菌，可以帮助我们的肠道抵抗病原体的定植。我们正在测试不同类型的益生菌阻止艰难梭菌在人体肠道模型中定植的能力，该模型模拟患有 CDI 的人类自然微生物环境。这是通过在三个烧瓶中培养来自健康人类粪便样本的细菌来完成的，这些烧瓶的 pH 值、营养物质和无氧条件类似于人类大肠。然后将抗生素和艰难梭菌添加到烧瓶中以建立“感染”，添加更多抗生素以去除艰难梭菌并模拟反复感染。然后将益生菌添加到系统中并检查益生菌是否可以预防艰难梭菌。我们还研究了无害的艰难梭菌（缺乏产生毒素的能力）与产生毒素的艰难梭菌菌株竞争并预防感染的能力。到目前为止，我们已经发现了一种无害的菌株，可以在广泛的实验条件下阻止艰难梭菌超级细菌菌株的生长和毒素产生，而这在之前尚未得到证实。这种控制艰难梭菌获取 ARG、生长和再定殖的三管齐下的方法将为开发 CDI 治疗方法开辟新途径。