The Electricidal Effect, a Novel Anti-Biofilm Strategy

描述（由申请人提供）：在现代临床实践中，生物膜细菌估计引起三分之二的感染。在生物膜中，微生物受到先天宿主防御和大多数可用的抗微生物剂的保护而不被杀死，最终在许多装置相关感染中需要移除装置（例如，人工关节感染）。鉴于抗微生物剂在生物膜相关器械感染管理中的失败，需要一种新型和创新的治疗和预防性非抗微生物方法。这种策略将限制常规抗微生物剂耐药性的出现，因为不需要常规抗微生物剂。这种策略还将限制与全身性抗微生物剂相关的毒性。 在我们的第一次提交中描述的初步体外研究表明，20至2000 A的电流基本上减少了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膜，我们将这种现象称为“杀电效应”（Antimicrob Ag Chemother 2009;53：41）。（用铜绿假单胞菌、S.金黄色葡萄球菌和S.表皮球菌、大肠杆菌和粪肠球菌各三个分离株以及变形链球菌物种组和白色念珠菌各一个分离株也显示出杀电作用。我们已经证明了电流对S是有效的。在兔异物感染模型中的表皮生物膜（Antimicrob Ag Chemother 2009;53：4064）。值得注意的是，直流电具有在临床实践中安全使用的先例（例如，加速骨折愈合）。 我们假设杀电效应对多种细菌和真菌生物膜（即，迄今为止的研究）。我们进一步假设，电流不仅可以治疗，而且还可以防止生物膜形成，并且这种策略是安全的。我们将建立最佳的体外和体内参数，以最大限度地提高杀菌效果，我们将确定是否观察到的生物膜相关的铜绿假单胞菌，S。金黄色葡萄球菌、epidermidis，E. coli、E.粪链球菌S. mutans和C.白色念珠菌），一般化至细菌和真菌的其它属、种和菌株。{We将使用功能（即，骨强度测试），整个器官（即，骨微计算机断层摄影术）和组织（即，组织形态测定法）评估。我们将评估电流是否能在体外和体内阻止细菌粘附到表面。这种效应的机制尚不清楚。我们假设氧化应激起作用。{We已经产生了新的初步数据，表明与野生型细菌相比，过氧化氢酶缺陷型细菌对杀电效应的敏感性增强，支持我们的机制假说。如果进一步的研究不支持这一假设，我们将评估分离作为一种机制。 本研究的结果预计将为使用杀电效应预防和治疗人类器械相关细菌感染提供依据和支持数据。该策略有可能消除在人类器械相关感染中取出器械的需要。这种方法不仅对生物膜有效，而且还将限制对常规抗菌剂的耐药性的出现，从而减少（无效）使用此类药物。

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.