Analyzing inoculum effect and optimal design of antibiotic treatment

描述(由申请者提供)：抗生素被誉为医学界最重要的治疗发现。然而，由于出现了抗药性细菌，它们变得越来越无效。除了开发新的抗生素外，迫切需要利用现有的抗生素设计更好的治疗方案。要实现这一目标，需要更好地了解细菌在个人或群体层面上抵抗或耐受抗生素治疗的各种方式。细菌耐受性的一个常见现象是接种效应：对于给定浓度的抗生素，其抑制细菌生长的能力随着细菌接种量的增加而降低。它的发生在临床上通常被认为是不可取的：它会由于抗生素剂量不足而增加受感染宿主的死亡率，并导致对细菌耐药性的高估。然而，接种效应发生的潜在机制仍然知之甚少。对于针对蛋白质合成机制(核糖体)的抗生素，我们的初步分析表明：(1)接种效应的关键决定因素是抗生素通过热休克反应诱导的核糖体成分的快速降解；(2)接种效应可以极大地影响抗生素治疗的效果。我们提出的研究旨在通过一种结合了数学建模、体外研究和体内研究的转换方法来检验这些假设。我们的愿景是，拟议的工作将产生对接种效应的机械理解，并导致针对表现出接种效应的病原体设计有效的治疗策略。这些结果将代表着朝着更有效地使用现有抗生素治疗细菌感染迈出了重要的一步。 公共卫生相关性：拟议的研究方法将提供对非遗传细菌对抗生素治疗耐受性这一常见但鲜为人知的现象的机械性见解。此外，拟议的研究将导致开发和评估针对细菌感染的有效治疗策略。

DESCRIPTION (provided by applicant): Antibiotics have been hailed as the single most significant therapeutic discovery in medicine. However, they have become increasingly ineffective due to emergence of antibiotic resistant bacteria. In addition to developing new antibiotics, there is a critical need to design better treatment protocols using existing antibiotics. Achieving this goal will require a better understanding of the myriad of ways by which bacteria can resist or tolerate antibiotic treatment at the level of individuals or populations. A common phenomenon of bacterial tolerance is the inoculum effect: for a given concentration of an antibiotic, its ability to inhibit bacterial growth decreases with the size of the bacterial inoculum. Its occurrence is often considered undesirable in the clinical setting: it can increase mortality rates of infected host due to insufficient dose of antibiotics and cause overestimation of bacterial resistance. However, the underlying mechanism by which the inoculum effect occurs remains poorly understood. For an antibiotic targeting the protein synthesis machinery (the ribosome), our preliminary analysis suggests that: (1) a critical determinant of inoculum effect is fast degradation of the ribosomal components induced by the antibiotic via the heat shock response; (2) the inoculum effect can drastically affect efficacy of antibiotic treatment. Our proposed research aims to examine these hypotheses by using a translational approach that integrates mathematical modeling, in vitro study, and in vivo study in the animal model of bacterial infections. It is our vision that the proposed work will generate mechanistic understanding of inoculum effect and lead to design of effective treatment strategies against pathogens that exhibit inoculum effect. These outcomes would represent a significant step toward more effective use of existing antibiotics to treat bacterial infections. PUBLIC HEALTH RELEVANCE: The proposed research approach will provide mechanistic insights into a common yet poorly understood phenomenon of non-genetic bacterial tolerance against antibiotic treatment. Furthermore, the proposed research will lead to development and evaluation effective treatment strategies against bacterial infections.