Characterization of the antibacterial activity of some antimicrobial-derived metabolites and their involvement in the development of antimicrobial resistance in bacteria of animal origin

抗菌素耐药性（AMR）通常被描述为“典型的一个健康问题”，是一个全球性的问题，对人类，动物和环境健康构成严重威胁。畜牧业如何促进AMR的传播仍在继续研究，结果表明，在农场动物中滥用抗生素对耐药细菌的选择产生了影响。动物源性细菌中AMR的表型和分子研究通常基于评估抗菌剂（母体分子）与这些细菌的AMR模式之间的联系。目前还不清楚抗菌代谢物-在动物体内母体分子生物降解后释放-是否参与AMR的选择和发展。因此，我的提案旨在首次在猪中表征来自一些医学上重要的抗菌剂（MIA）的主要代谢产物的体外和体内抗菌活性，并表征与其母体分子相比，细菌对这些化合物的耐药性演变。将使用肉汤微量稀释法评估细菌对MIA及其代谢产物的敏感性，并主要使用聚合酶链反应（PCR）进行AMR细菌的基因型表征。将使用连续发酵模型来表征在模拟猪肠道中发现的条件下抗菌代谢物的稳定性。将使用实验性断奶后腹泻模型在体内表征主要抗菌剂衍生代谢产物或其母体分子经口给药后的抗菌活性和AMR细菌的选择。最具创新性的分子方法（高通量测序、全基因组测序、全宏基因组鸟枪测序等）将被用于这项研究计划。我们预计，一些抗微生物衍生的代谢产物将与显着的抗菌活性相关，并参与AMR细菌的选择，而它们在猪体内的持续时间比它们的母体分子更长。我的研究计划将在真实的现场条件下产生新的发现，将提供更好地控制AMR通过食物链传播的数据，将开发概念验证以定义猪用抗菌剂的微生物停药期，并将在抗菌剂衍生代谢物的表征及其在猪体内的持久性方面取得突破性进展。这些贡献将有助于加拿大和世界各地的研究人员、兽医和生产商在全球努力应对AMR构成的重大公共卫生威胁。为了帮助实现这些目标，我将确保高素质人员（HQP）得到培训，该计划将扩大成为一个国际参考实验室，专门研究抗菌药物衍生代谢物。

Often described as the "quintessential One Health issue," antimicrobial resistance (AMR) is a global concern that poses a serious threat to human, animal, and environmental health. How the livestock sector contributes to the spread of AMR continues to be studied, with results pointing to the misuse of antimicrobials in farm animals having an impact on the selection of drug-resistant bacteria. The phenotypic and molecular study of AMR in bacteria of animal origin is often based on assessing the link between antimicrobials (parent molecules) and the AMR pattern of these bacteria. It is still mostly unknown if antimicrobial metabolites - released after the biodegradation of parent molecules within the animal - are involved in the selection and development of AMR. My proposal therefore aims to characterize, for the first time in pigs, both the in vitro and in vivo antibacterial activity of the major metabolites derived from some medically important antimicrobials (MIAs) and to characterize the evolution of bacterial resistance to these compounds compared to their parent molecules. Bacterial susceptibility to the MIAs and their metabolites will be assessed using the broth microdilution method, and genotypic characterization of AMR bacteria will be performed mostly using the Polymerase Chain Reaction (PCR). A continuous fermentation model will be used to characterize the stability of antimicrobial metabolites in conditions mimicking those found in swine intestines. An experimental post-weaning diarrhea model will be used to characterize in vivo both the antibacterial activity and the selection of AMR bacteria following the oral administration of the major antimicrobial-derived metabolites or their parent molecules. The most innovative molecular methods (high throughput sequencing, whole genome sequencing, whole-metagenome shotgun sequencing, etc.) will be used in this research program. We anticipate that some antimicrobial-derived metabolites will be associated with significant antibacterial activity and are involved in the selection of AMR bacteria, while they persist longer in a pig's body than their parent molecules. My research program will generate new findings under real field conditions, will provide data on better controlling AMR spread through the food chain, will develop a proof of concept to define a microbiological withdrawal period for antimicrobials used in pigs, and will produce ground-breaking advances in the characterization of antimicrobial-derived metabolites and their persistence in the bodies of pigs. These contributions will be useful to researchers, veterinarians, and producers in Canada and around the world in our global effort to contend with the major public health threat that AMR poses. To help achieve these goals, I will ensure that Highly Qualified Personnel (HQP) are trained and that the program will expand to become an international reference laboratory specialized in the study of antimicrobial-derived metabolites.