Tetracycline resistance: the Achilles' heel of antibiotic resistance?

 描述(申请人提供)：抗菌素耐药性(AMR)是对全球健康安全的重大威胁，也是一项单一健康挑战，因为人类和动物医学中抗生素的使用都会导致AMR细菌的出现、放大、持续和传播。AMR的控制目前主要取决于谨慎使用原则和监管控制，以及开发替代抗生素和感染控制措施。然而，限制抗生素的使用只有在存在与携带AMR特征相关的显著适应成本的情况下才适用于现有的AMR人群。在实践中，这种被动的衰退机制在很大程度上是无效的，因为隐藏抗性性状的适应成本很低。该项目将开发一种全新的策略，人为地诱导对AMR细菌的高适应成本，并积极地将这些微生物赶出选定的种群。焦点将是只有在四环素抗生素存在的情况下才能表达的四环素外排泵。S通过将细菌暴露于一种不损害四环素敏感细菌的降解的四环素来诱导Tet(A)和Tet(B)外排泵的表达。众所周知，在辅因子存在的情况下表达这些外排泵的组合会给四环素耐药细菌带来显著的适应成本，但这个想法从未扩展到种群水平的控制。该项目将检验核心假设，即在存在特定辅助因子的情况下，四环素耐药外排泵的表达将给宿主细菌带来显著的适应成本，并且可以利用这一机制来降低抗生素耐药细菌的流行率。通过一系列基于实验室和田间的实验，该项目试图(1)确定主动选择是否可以推广到更多的四环素外排泵和细菌病原体。这一目标将确定辅助因子，估计不同四环素耐药细菌的反应差异，并确定负责诱导四环素外排表达的降解四环素的成分。(2)确定口服不含辅因子的改良四环素产品是否可以在动物模型中降低多重耐药大肠杆菌的患病率。这一目标将使用鸡模型来确定是否可以使用主动选择来限制AMR种群，否则AMR种群可能会传播给人。(3)确定添加有或没有辅因子的改良四环素是否可以降低土壤水库中发现的耐药大肠杆菌的流行率。从长远来看，AMR细菌的储备库可能会发挥重要作用 这些细菌在环境中的持久性。如果我们能够通过主动选择有选择地针对初级水库，这将降低食物链中AMR细菌的总体流行率，可能还会降低其他环境中包括医院在内的AMR细菌的流行率。使用主动选择来对抗AMR细菌是完全新颖和创新的，与依赖被动下降相比，它将导致AMR细菌的快速丧失。它还有一个优点，那就是让对抗生素敏感的细菌种群基本上不受影响，从而限制对正常微生物的破坏。 弗洛拉。

 DESCRIPTION (provided by applicant): Antimicrobial resistance (AMR) is a significant threat to global health security and a one-health challenge because antibiotic use in both human and animal medicine contributes to the emergence, amplification, persistence and dissemination of AMR bacteria. Control of AMR currently relies primarily on prudent use principles and regulatory controls and on development of alternative antibiotics and infection control measures. However, limiting antibiotic use only works against existing AMR populations if there is a significant fitnes cost associated with carriage of AMR traits. In practice, this PASSIVE decay mechanism is largely ineffective because fitness costs for harboring resistance traits are low. This project wil develop a completely novel strategy to artificially induce a high fitness cost against AMR bacteria and ACTIVELY drive these microbes out of select populations. The focus will be tetracycline efflux pumps that are only expressed in the presence of a tetracycline antibiotic. It s possible to induce expression of tet(A) and tet(B) efflux pumps by exposing the bacteria to a degraded tetracycline that does not harm tetracycline-sensitive bacteria. A combination of expressing these efflux pumps in the presence of cofactors is known to impose a significant fitness cost on the tetracycline-resistant bacteria, but this idea has never been extended to population-level control. This project will test the central hypothesis that in the presence of specific cofactors, expression of tetracycline-resistance efflux pumps will impose a significant fitness cost on the host bacterium and this mechanism can be exploited to reduce the prevalence of antibiotic-resistant bacteria. With a series of lab-based and field-based experiments, this project seeks to (1) Determine if active selection can be generalized to additional tetracycline efflux pumps and to bacterial pathogens. This aim will identify cofactors, estimate the variance of the response by different tetracycline-resistant bacteria, and identify th component of the degraded tetracycline that is responsible for inducing expression of tetracycline efflux. (2) Determine if oral administration of a modified tetracycline product, with r without a cofactor, can reduce the prevalence of multidrug resistant E. coli in an animal model. This aim will employ a chicken model to determine if active selection can be used to limit AMR populations that could otherwise be disseminated to people. (3) Determine if addition of a modified tetracycline, with or without a cofactor, can reduce the prevalence of resistant E. coli found in soil reservoirs. Reservoirs of AMR bacteria likely play an important role in the long-term persistence of these bacteria in the environment. If we are able to selectively target primary reservoirs by active selection, this will reduce the overall prevalence of AMR bacteria in food chain and possibly in other environments including hospitals. Employing active selection against AMR bacteria is completely novel and innovative, and will result in rapid loss of AMR bacteria as compared to reliance on passive decline. It also has the advantage of leaving the antibiotic-susceptible population of bacteria largely unaffected and thus limit disruption of normal microbial flora.