Development of Strategies for the Treatment of Biofilm Infections in Indwelling Medical Devices

生物膜是一种进化适应，允许细菌聚集在一起并经历生理和形态变化，改变基因调控和产生胞外聚合物（EPS）。EPS作为一种胶水，可以有效地将生物膜粘附到几乎任何表面，但它也允许释放细胞外DNA，蛋白质和更多的辅助因子，从而促进对抗菌剂的耐药性和耐受性。细菌生物膜存在于从水管到留置医疗器械（如导管）的各种环境中。生物膜感染在体内诊断可能具有挑战性，并且难以根除。一旦建立，EPS保护细菌免受流体流动和质量运输，导致基质对抗生素和免疫细胞具有高度抗性。这是由于与生物膜群落相关的许多因素;多微生物生态系统内的各种细胞通过群体感应进行通信，并可能在细胞与细胞之间赋予抗菌素抗性基因。据估计，消除生物膜中的细菌所需的抗生素水平可能比生物膜细胞高上千倍，这可能是由于缺乏药物通过生物膜EPS的有效灌注，或者可能表明药物结合，这可能导致不希望的副作用。该项目将涉及收集实验数据，用于生物膜形成的时间分辨表征和使用谢菲尔德抗菌素耐药性和生物膜中心（SCARAB）内最先进的设备治疗生物膜感染，该中心最近由InnovateUK资助。从而限制了生物膜内抗微生物剂抗性和耐受性的发展。有证据表明，80%的人类细菌感染与生物膜相关（Roberts et al.，2015年），因此，对新治疗的需求越来越迫切。替代策略包括开发防止细菌粘附于表面并因此形成生物膜的材料涂层，或响应于某些类型的细菌而递送新型治疗剂的动态抗菌涂层。然而，生物膜通常由多种微生物群落组成，其组成因国家而异。因此，生物膜相关感染的有效治疗是一个复杂的问题，其中微生物的协同或拮抗作用可能对治疗产生影响，这还没有得到很大的探索。导管相关尿路感染（CAPTOTIS）是最常见的医院感染之一，导致危及生命的病症，例如脓毒症，并且对医院和保健设施造成很大的经济负担。将开发一个基于实验室的模型系统，包括临床相关细菌的社区：大肠杆菌，铜绿假单胞菌，粪肠球菌和奇异变形杆菌。这项研究将探索多微生物生物膜生长的机制，旨在模拟导管的流动环境，并测试社区对新兴治疗策略的反应。这可能包括使用涂层材料和防污材料防止粘连，或采用新技术处理生物膜，其中可能包括抗生素膜肽。我们将与医学、牙科和健康学院的同事合作，并与利益相关者合作：设备的尊严，NHS医疗保健技术合作，以确保制定的战略是相关的医疗保健提供者。一、Kragh，K.，Bjarnsholt，T.和Diggle，S.（2015年）。体外实验在了解生物膜和慢性感染方面的局限性。Journal of Molecular Biology，427（23），pp.3646-3661.

Biofilms are evolutionary adaptations that allow bacteria to aggregate together and undergo physiological and morphological changes, altered gene regulation and generation of extracellular polymeric substance (EPS). EPS acts as a glue that effectively adheres the biofilm to almost any surface, but it also allows for the release of extracellular DNA, proteins and many more cofactors that encourage resistance and tolerance of antimicrobials. Bacterial biofilms are found in diverse environments from water pipes to indwelling medical devices such as catheters. Biofilm infections can be challenging to diagnose in vivo and difficult to eradicate. Once established, the EPS protects the bacteria against fluid flow and mass transport resulting in a matrix highly resistant to antibiotics and immune cells. This is due to many factors associated with the biofilm community; various cells within the polymicrobial ecosystem communicate via quorum sensing and may confer antimicrobial resistance genes from cell to cell. It has been estimated that the levels of antibiotics required to eliminate bacteria in biofilms can be up to a thousand times higher than for planktonic cells, this may due to lack of effective perfusion of the drugs through the biofilm EPS or it could indicate drug binding, which may result in unwanted side-effects. This project will involve the collection of experimental data for the time-resolved characterisation of biofilm formation and treatment of biofilm infections using state-of-the-art equipment within the Sheffield Centre for Antimicrobial Resistance and Biofilms (SCARAB), recently funded by InnovateUK.There is an increasing need for strategies that involve the treatment of bacteria in biofilms without administering antibiotics, thus limiting the development of antimicrobial resistance and tolerance within biofilms. There is evidence to suggest that 80% of human bacterial infections are biofilm related (Roberts et al., 2015) and therefore a need for new treatments is ever more urgent. Alternative strategies include the development of material coatings that prevent adherence of bacteria to surfaces, and hence biofilm formation, or dynamic antibacterial coatings that deliver novel therapeutics in response to certain types of bacteria. However, biofilms typically consist of polymicrobial communities, the make-up of which is country-specific. Therefore, effective treatment of biofilm related infections is a complex problem where the synergistic or antagonistic effects of the microorganisms may have an impact on treatment that has not been greatly explored.Catheter-associated urinary tract infections (CAUTIS) are one of the most common nosocomial infections and can be both dangerous to the patient, resulting in life-threatening conditions such as sepsis and represent a large financial burden to hospitals and healthcare facilities. A lab-based model system for CAUTIs will be developed involving communities of clinically relevant bacteria: Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis and Proteus mirabilis. This research will explore mechanisms of polymicrobial biofilm growth in a flow environment designed to mimic that of catheters and test the community response to emerging strategies for treatment. This may include the prevention of adhesion using coated materials and antifouling materials or employing novel technologies for the treatment of biofilms which could include antibiofilm peptides.We will collaborate with colleagues in the Faculty of Medicine, Dentistry and Health as well as work with stakeholders: Devices for Dignity, an NHS healthcare technology co-operative, to ensure that strategies developed are relevant to healthcare providers.ReferencesRoberts, A., Kragh, K., Bjarnsholt, T. and Diggle, S. (2015). The Limitations of In Vitro Experimentation in Understanding Biofilms and Chronic Infection. Journal of Molecular Biology, 427(23), pp.3646-3661.