The Electricidal Effect, a Novel Anti-Biofilm Strategy

描述(由申请人提供)：在现代临床实践中，生物被膜细菌估计引起三分之二的感染。在生物膜中，微生物受到天然宿主防御和大多数可用的抗菌剂的保护，最终导致许多设备相关感染(例如假肢关节感染)需要移除设备。鉴于抗菌药在治疗生物膜相关设备感染方面的失败，需要一种新的、创新的治疗和预防非抗菌药的方法。这种战略将限制常规抗菌剂耐药性的出现，因为不需要常规抗菌剂。这种战略还将限制与全身性抗菌剂有关的毒性。我们第一份提交的初步体外研究表明，20到2000&lt；A的电流显著减少了已建立的铜绿假单胞菌、金黄色葡萄球菌和表皮葡萄球菌生物被膜，我们将这种现象称为“电杀灭效应”(Antimmicrob Ag Chemther 2009；53：41)。{两个新的铜绿假单胞菌、金黄色葡萄球菌和表皮葡萄球菌分离株，三个大肠杆菌和粪肠球菌分离株，以及每个变形链球菌和白色念珠菌的单独分离株产生的初步数据也显示了电杀灭作用。}我们已经在兔异物感染模型中证明了电流对表皮葡萄球菌生物膜的活性(Antimmicrob Ag Chemther 2009；53：4064)。值得注意的是，直流电在临床实践中有过安全使用的先例(例如，加速骨折愈合)。我们假设，这种杀电效应对各种细菌和真菌生物膜具有广泛的活性(即，超出了迄今所研究的那些生物膜)。我们进一步假设，电流不仅可以治疗生物膜，还可以防止生物膜的形成，而且这种策略是安全的。我们将建立最佳的体外和体内参数，以最大限度地发挥电杀灭作用，并确定所观察到的对生物膜相关的铜绿假单胞菌、金黄色葡萄球菌、表皮葡萄球菌、{大肠杆菌、粪便大肠杆菌、变形链球菌和白色念珠菌}的杀灭是否适用于其他属、种和菌株的细菌和真菌。我们将使用功能(即骨强度测试)、整个器官(即骨骼微计算机断层扫描)和组织(即组织形态计量学)评估在我们的动物模型中与输送电流相关的不良影响(如果有)。}我们将在体外和体内评估电流是否阻止细菌附着到表面。这种效应背后的机制尚不清楚。我们假设氧化应激起了一定作用。{我们已经产生了新的初步数据，与野生型细菌相比，过氧化氢酶缺陷细菌增强了对电击效应的敏感性，支持了我们的机制假说。如果进一步的研究不支持这一假说，我们将评估脱离作为一种机制。}这项研究的结果有望为使用杀电效应预防和治疗人类设备相关细菌感染提供理论基础和支持数据。这一策略有可能在人类设备相关感染中消除移除设备的需要。这种方法不仅对生物被膜有积极作用，而且还将限制对传统抗菌剂的耐药性的出现，从而减少此类药物的(无效)使用。

DESCRIPTION (provided by applicant): Biofilm bacteria are estimated to cause two thirds of infections in modern clinical practice. In biofilms, microorganisms are protected from killing by innate host defenses and most available antimicrobial agents, culminating in the need for device removal in many device-associated infections (e.g., prosthetic joint infection). Given the failure of antimicrobics in the management of biofilm-associated device infections, a novel and innovative therapeutic and preventive non-antimicrobial approach is needed. Such a strategy would limit emergence of conventional antimicrobial resistance, as conventional antimicrobial agents would not be needed. Such a strategy would also limit toxicity associated with systemic antimicrobial agents. The preliminary in vitro studies described in our first submission demonstrated that electrical currents of 20 to 2000 <A substantially reduced established Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis biofilms, a phenomenon we termed the "electricidal effect" (Antimicrob Ag Chemother 2009;53:41). {Preliminary data generated with two new isolates each of P. aeruginosa, S. aureus, and S. epidermidis, three isolates each of Escherichia coli and Enterococcus faecalis, and single isolates of each of Streptococcus mutans species group and Candida albicans also demonstrate an electricidal effect.} We have shown that electrical current is active against S. epidermidis biofilms in a rabbit foreign body infection model (Antimicrob Ag Chemother 2009;53:4064). Notably, direct current has a precedent of being safely used in clinical practice (e.g., to accelerate fracture healing). We hypothesize that the electricidal effect is broadly active against a variety of bacterial and fungal biofilms (i.e., beyond those studied to date). We further hypothesize that electrical current will not only treat, but will also prevent biofilm formation, and that this strategy is safe. We will establish optimal in vitro and in vivo parameters to maximize the electricidal effect, and we will determine whether the observed killing of biofilm-associated P. aeruginosa, S. aureus, S. epidermidis, {E. coli, E. faecalis, S. mutans and C. albicans}, generalizes to other genera, species and strains of bacteria and fungi. {We will characterize adverse effects (if any) associated with delivery of electrical current in our animal model using functional (i.e., bone strength testing), whole organ (i.e., bone micro-computed tomography) and tissue (i.e., histomorphometry) assessments.} We will assess whether electrical current prevents bacterial adhesion to surfaces in vitro and in vivo. The mechanism that underlies this effect is unknown. We hypothesize that oxidative stress plays a role. {We have generated new preliminary data showing that, compared with wild-type bacteria, catalase-deficient bacteria have enhanced susceptibility to the electricidal effect, supporting our mechanistic hypothesis. If further studies do not support this hypothesis, we will evaluate detachment as a mechanism.} Results of this study are expected to provide a rationale and supporting data for the use of the electricidal effect for prevention and treatment of device-related bacterial infections in humans. This strategy has the potential to eliminate the need for device removal in human device-related infections. Not only will this approach be active against biofilms, but it will limit the emergence of resistance to conventional antimicrobial agents, resulting in less (futile) use of such drugs.