Antibiotics for Recalcitrant Infection

描述(由申请人提供)：该项目的目标是开发一种能够消毒顽固性慢性感染的治疗方法，如深部脓肿、骨髓炎、心内膜炎和留置装置的生物膜。这些感染中的许多基本上是无法治疗的，并导致大量发病率和死亡率。在许多情况下，感染的顽固性不是由耐药性引起的。相反，增长缓慢的生物膜群体拥有静止期和休眠的持久细胞，这些细胞对抗菌剂的杀戮具有高度的耐受性。 当抗生素浓度下降时，这些细胞可以生长并重新滋生生物膜。在革兰氏阳性金黄色葡萄球菌中，似乎固定培养的主要是耐药细胞，这些细胞对传统抗生素的杀灭几乎不敏感。有许多独立的、多余的持久形成机制，这些专门的存活细胞没有一个现实的靶点可以用于药物开发。为了发挥作用，所有现有的杀菌抗生素都需要活性靶点，而它们会破坏这些靶点。我们推断，如果一个小分子可以同时激活和破坏一个细胞靶标，那么持久者可能会被杀死。我们发现，酰基多肽(ADEP)激活了休眠持续体中的ClpP蛋白酶，迫使细胞自我消化。为了减少耐药性的发展，ADEP与利福平联合应用。这种组合在单次给药后完全消毒了中性粒细胞减少的小鼠模型中深层次的金黄色葡萄球菌生物膜感染。最好的传统抗生素，无论是单独使用还是联合使用，效果都很小。这种模型模拟了免疫功能低下患者中最难治疗的慢性感染。在这个项目中，我们将确定最有希望的消毒药物组合。将使用MRSA感染的深层次中性粒细胞减少的大腿模型和体内生物膜组织笼模型来评估组合的PK、PD和疗效。一旦得到验证，这种联合疗法将进入第二阶段的临床前研究，导致IND和随后的药物临床试验。

DESCRIPTION (provided by applicant): The goal of the project is to develop a therapeutic capable of sterilizing recalcitrant chronic infections such as deep-seated abscess, osteomyelitis, endocarditis, and biofilms of indwelling devices. Many of these infections are essentially untreatable and lead to substantial morbidity and mortality. In many cases, recalcitrance of an infection is not caused by drug resistance. Rather, a slow-growing biofilm population harbors stationary phase and dormant persister cells that are highly tolerant to killing by antimicrobials. When antibiotic concentration drops, these cells can grow and repopulate the biofilm. In Gram-positive S. aureus, it appears that a stationary culture is made mostly of drug tolerant cells which are virtually insensitive to killing by traditional antibiotics. There are many independent, redundant mechanisms of persister formation, and these specialized survivor cells do not have a realistic target which could be exploited for drug development. In order to act, all existing bactericidal antibiotics require active targets which they corrupt. We reasoned that persisters could be killed if a small molecule could simultaneously activate and corrupt a cellular target. We find that acyldepsipeptide (ADEP) activates the ClpP protease in dormant persisters, forcing the cell to self-digest. In order to diminish resistance development, ADEP was combined with rifampicin. The combination completely sterilized a deep- seated biofilm infection of S. aureus in a neutropenic mouse model after a single dose. The best conventional antibiotics, alone or in combination, had very little effect. This model emulates the most difficult to treat chronic infection in immunocompromised patients. In this project, we will identify the most promising sterilizing combinations of drugs. Combinations will be evaluated for PK, PD, and efficacy using a deep-seated neutropenic thigh model of MRSA infection, and in an in vivo biofilm tissue-cage model. Once validated, the combination therapeutic will enter into preclinical investigation in Phase II, leading to an IND, and subsequent clinical trials of the drug.