Investigation into methods for giving early warning and prevention of urinary catheter blockage

导尿管相关的尿路感染已被确定为NHS的优先领域，与医疗相关的感染每年花费约10亿英镑。除了经济负担和对患者结果的关注外，NHS还承诺减少抗菌素耐药性(AMR)的负担，而感染预防是其中的关键部分。该项目的目标是开发一种低成本的治疗尿素酶阳性导管相关性尿路感染的方法。这样一个小分子将通过导管球囊输送到感染部位进行治疗。这直接符合EPSRC在医疗保健技术方面的职责，特别是在(1)开发未来疗法；(2)优化治疗；(3)改变社区卫生和护理方面。为什么导尿管堵塞？奇异变形杆菌是一种革兰氏阴性细菌，常见于长期导尿的患者的膀胱中。奇异肺炎杆菌在导管上形成生物膜，并分泌酶尿素酶。尿素酶，允许奇异假单胞菌利用尿素作为氮源，允许细菌生长。尿素的水解会产生碳酸和两个氨分子。氨会将膀胱中的尿液pH值提高到7.5-9，而健康的酸性尿液pH值为5.5-6.5。因此，鸟粪石MgNH4PO4.6H2O和磷灰石Ca10(PO4CO3OH)6(OH)2的局部过饱和和沉淀进入导管管腔会导致研磨结晶沉积物结合到导管管腔内外表面。在将导管插入受感染的膀胱后，在短短16小时内，导管管腔可能完全闭塞。项目2-巯基乙酰胺(2-MA)已被鉴定为一种独特的抗尿素酶小分子。该分子价格低廉，易于合成，但重要的是，它在抑制尿素酶方面比任何其他临床使用的尿素酶抑制剂都更有效，如在美国销售的乙氧肟酸(AHA)和在欧洲销售的Uronefrex。AHA的主要问题是它具有强烈的毒性，在欧洲很少使用。初步的体外研究显示了非常有希望的结果，2-MA比AHA有效得多，而且毒性更小。博士计划第1部分：2-MA及其类似物的合成2-MA是一类相关化合物，都具有相同的化学“弹头”。将合成一个基于2-MA的化合物文库，并测试它们的尿素酶抑制特性(第二部分)、毒性(第三部分)和通过导管球囊传递(第二部分)。第二部分：使用Scarlet已建立的测试方案在膀胱模型中测试2-MA及其类似物第一部分中制作的化合物文库将在我们的体外膀胱中进行测试，测试结果包括对导管堵塞的抑制、米氏假单胞菌生物膜形成的减少、尿液pH值、米氏假单胞菌活细胞的减少。在这项工作中，大约3-4种铅化合物将在第三阶段进行毒性测试第三部分：毒性测试将使用血液溶血毒性测试和真核细胞活性分析来评估铅化合物的毒性，并以商业尿素酶抑制剂AHA为基准。第五部分：通过导尿管气囊输送的测试尿管通过充水气球在膀胱中保持在适当的位置。我们的尿素酶抑制剂的概念将是使用气囊将药物直接输送到膀胱中。这将依赖于穿过超薄硅胶气球的小分子。我们将研究添加辅料以协助药物转移。第五部分：临床研究的准备一旦确定和测试了先导化合物(上图)，我们将与皇家联合医院一级泌尿科顾问医生埃德·杰弗里先生密切合作

Catheter-associated urinary tract infections have been identified as a priority area for the NHS, with healthcare-associated infections costing some £1bn per year. As well as the economic burden and a concern for patient outcomes, the NHS has a commitment to reducing the burden of antimicrobial resistance (AMR), and infection-prevention is a key part of this. The objective of the project is to develop a low-cost treatment for urease positive catheter associated urinary tract infections. Whereby a small molecule will be delivered through the catheter balloon to treat at site of infection. This fits directly to the EPSRC remit in healthcare technologies specifically in the areas of (1) developing future therapies; (2) optimising treatment; and (3) transforming community health and care. Why do urinary catheters block?Proteus mirabilis is a Gram-negative bacterium which is commonly found in the bladder of patients who are long term catheterised. P. mirabilis forms biofilms on the catheter and secretes the enzyme urease. Urease, allows P. mirabilis to exploit urea as a nitrogen source, allowing the bacteria to grow. Urea hydrolysis results in the production of carbonic acid and two molecules of ammonia. Ammonia raises the urinary pH in the bladder to pH 7.5-9, compared to healthy, acidic urine pH of 5.5-6.5. Consequently, local supersaturation and precipitation of struvite MgNH4PO4.6H2O and apatite, Ca10(PO4CO3OH)6(OH)2) into the catheter lumen causes abrasive crystalline deposits to become incorporated onto the catheter lumen external and internal surfaces. Total occlusion of the catheter lumen may follow blocking the catheter in as little as 16 hours from placement of catheter into an infected bladder.The Project2-Mercaptoacetamide (2-MA) has been identified as a unique anti-urease small molecule. This molecule is cheap and easy to synthesise, but importantly has shown to be more effective at urease enzyme inhibition than any other urease inhibitor used clinically such as Acetohydroxamic acid (AHA), which is marketed as Lithostat in the USA, and Uronefrex in Europe. The principal problem with AHA is that it is intensely toxic and is rarely used in Europe. Preliminary in-vitro studies have shown very promising results, with 2-MA being far more effective than AHA, as well as being less toxic.The Ph.D programmePart 1: Synthesis of 2-MA and analogues2-MA is one of a family of related compounds, all with the same chemical 'warhead'. A library of compounds based on 2-MA will be synthesised and tested for their urease inhibition properties, (part 2) toxicity (part 3) and delivery through the catheter balloon (part 2). Part 2: Testing of 2-MA and analogues in bladder model Using Scarlet's established test protocols the compound library made in part 1 will be tested in our in-vitro bladder with inhibition to catheter blockage, reduction in P. mirablis biofilm formation, urinary pH, reduction in P. mirablis viable cells all measured as outcomes. From this work, around 3-4 lead compounds will be taken through for toxicity testing in phase 3.Part 3: Toxicity testingToxicity testing using blood haemolysis and eukaryotic cell viability assays will be used to assess toxicity of lead compounds, benchmarked against the commercial urease inhibitor, AHA.Part 5: testing of delivery through the catheter balloonUrinary catheters are kept in place in the bladder via the 'inflation' of a balloon with water. The concept for delivery of our urease inhibitors will be to use the balloon to deliver the drug directly into the bladder. This will rely on the small molecules crossing the ultrathin silicone balloon. We will investigate adding excipients to assist in drug transfer.Part 5: Preparation for clinical studyOnce lead compounds have been identified and tested (above) we will work closely with Mr Ed Jefferies, consultant urologist at the Royal United Hospital i