The use of animal models with depleted intestinal microbiota has recently increased thanks to the huge interest in the potential role of these micro-organisms in human health. In particular, depletion of gut bacteria using antibiotics has recently become popular as it represents a low cost and easy alternative to germ-free animals. Various regimens of antibiotics are used in the literature, which differ in composition, dose, length of treatment and mode of administration. In order to help investigators in choosing the most appropriate protocol for their studies, we compared here three modes of antibiotic delivery to deplete gut bacteria in C57Bl/6 mice. We delivered one of the most frequently used combination of antibiotics (a mix of ampicillin, neomycin, metronidazole and vancomycin) either ad libitum in drinking water or by oral gavage once or twice per day. We quantified the global bacterial density, as well as the abundance of specific bacterial and fungal taxa, in mouse feces in response to antibiotics exposure. We observed that oral gavage once a day with antibiotics is not a reliable method as it occasionally triggers hyperproliferation of bacteria belonging to the Escherichia/Shigella taxon and leads, as a consequence, to a moderate decrease in fecal bacterial density. Antibiotics delivery by oral gavage twice a day or in drinking water induces in contrast a robust and consistent depletion of mouse fecal bacteria, as soon as 4 days of treatment, and is associated with an increase in fecal moisture content. Extending exposure to antibiotics beyond 7 days does not improve total bacteria depletion efficiency and promotes fungal overgrowth. We show in addition that all tested protocols impact neither gut microbiota recolonization efficiency, 1 or 2 weeks after the stop of antibiotics, nor mice body composition after 1 week of treatment. Our study provides key experimental data and highlights important parameters to consider before selecting an appropriate protocol for antibiotic-mediated depletion of gut bacteria, in order to optimize the accuracy and the reproducibility of results and to facilitate comparison between studies.

中文翻译：

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不同抗生素给药方式对小鼠肠道微生物群消耗效率和身体成分的比较

由于对这些微生物在人类健康中的潜在作用的巨大兴趣，最近增加了肠道菌群耗尽的动物模型的使用。特别是，使用抗生素去除肠道细菌最近变得流行，因为它代表了一种低成本且易于替代无菌动物的方法。文献中使用了各种抗生素方案，它们的组成、剂量、治疗时间和给药方式各不相同。为了帮助研究人员为他们的研究选择最合适的方案，我们在这里比较了三种抗生素递送模式，以消耗 C57Bl/6 小鼠的肠道细菌。我们提供了一种最常用的抗生素组合（氨苄青霉素、新霉素、甲硝唑和万古霉素）在饮用水中随意饮用或每天一次或两次口服管饲。我们量化了小鼠粪便中抗生素暴露的全球细菌密度，以及特定细菌和真菌类群的丰度。我们观察到，每天一次用抗生素口服管饲不是一种可靠的方法，因为它偶尔会引发属于埃希氏菌/志贺氏菌分类群的细菌过度增殖，并因此导致粪便细菌密度适度降低。相比之下，通过每天两次口服灌胃或在饮用水中输送抗生素，在治疗 4 天后会引起小鼠粪便细菌的强烈和持续消耗，并且与粪便水分含量增加有关。将抗生素暴露时间延长超过 7 天不会提高总细菌消耗效率并促进真菌过度生长。此外，我们还表明，所有经过测试的方案都不会影响抗生素停用后 1 或 2 周的肠道微生物群重新定殖效率，也不会影响治疗 1 周后的小鼠身体成分。我们的研究提供了关键的实验数据，并强调了在选择合适的抗生素介导的肠道细菌消耗方案之前要考虑的重要参数，以优化结果的准确性和可重复性，并促进研究之间的比较。治疗1周后也没有小鼠的身体成分。我们的研究提供了关键的实验数据，并强调了在选择合适的抗生素介导的肠道细菌消耗方案之前要考虑的重要参数，以优化结果的准确性和可重复性，并促进研究之间的比较。治疗1周后也没有小鼠的身体成分。我们的研究提供了关键的实验数据，并强调了在选择合适的抗生素介导的肠道细菌消耗方案之前要考虑的重要参数，以优化结果的准确性和可重复性，并促进研究之间的比较。