The Electricidal Effect, a Novel Anti-Biofilm Strategy

描述（由申请人提供）：据估计，在现代临床实践中，生物膜细菌导致了三分之二的感染。在生物膜中，微生物被先天宿主防御和大多数可用的抗菌剂保护而不被杀死，最终导致许多器械相关感染（例如，假体关节感染）需要移除器械。鉴于抗菌药物在生物膜相关器械感染管理中的失败，需要一种新颖和创新的治疗和预防性非抗菌方法。这种策略将限制常规抗微生物药物耐药性的出现，因为不再需要常规抗微生物药物。这种策略也将限制与全身抗菌剂相关的毒性。我们在第一份报告中描述的初步体外研究表明，20至2000 <A的电流大大减少了铜绿假单胞菌、金黄色葡萄球菌和表皮葡萄球菌的生物膜，我们将这种现象称为“电杀效应”（Antimicrob Ag Chemother 2009;53:41）。{铜绿假单胞菌、金黄色葡萄球菌和表皮葡萄球菌各分离两株，大肠杆菌和粪肠球菌各分离三株，变形链球菌和白色念珠菌各分离一株产生的初步数据也显示出电杀作用。我们已经在兔异物感染模型中证明电流对表皮葡萄球菌生物膜有活性（Antimicrob Ag Chemother 2009;53:4064）。值得注意的是，直流电在临床实践中有安全使用的先例（例如，加速骨折愈合）。我们假设电杀菌作用对各种细菌和真菌生物膜广泛有效（即，超出迄今为止研究的范围）。我们进一步假设，电流不仅可以治疗，还可以防止生物膜的形成，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，以最大限度地提高电杀效果，我们将确定是否观察到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、{E。大肠杆菌，粪大肠杆菌，变形链球菌和白色念珠菌，推广到其他属，种和菌株的细菌和真菌。{我们将通过功能（即骨强度测试）、全器官（即骨微计算机断层扫描）和组织（即组织形态测量）评估来描述与电流传递相关的不良反应（如果有的话）。我们将评估电流是否能阻止细菌在体外和体内表面的粘附。这种效应背后的机制尚不清楚。我们假设氧化应激起了作用。{我们已经生成了新的初步数据，表明与野生型细菌相比，过氧化氢酶缺乏的细菌对电杀效应的敏感性增强，支持我们的机制假设。如果进一步的研究不支持这一假设，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电杀效应来预防和治疗人类与器械相关的细菌感染提供理论依据和支持数据。这种策略有可能消除在人类设备相关感染中移除设备的需要。这种方法不仅对生物膜有效，而且还将限制对传统抗菌药物的耐药性的出现，从而减少（无用的）使用这类药物。

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.