摘要

      减少抗生素的使用是减少家畜抗生素耐药性的必要步骤，但许多抗生素抗性基因可以持续数年，甚至在没有抗生素的环境中。在这项研究中，我们研究了抗生素naivedo的三种粪便复合微生物群落对抗生素暴露的水坝中的试剂盒微生物群的潜在驱动力，并击败携带抗生素抗性基因的细菌。粪便复合微生物群落要么口服，要么简单地作为新鲜粪便颗粒添加到4到5个保持母亲粪便清洁的巢穴中。此外，对照组按照一般农场做法（即每周清洁一次）清理了四个巢穴，以备母亲粪便之用，并处理了五个巢穴。在断奶期，我们通过对每窝一个试剂盒的16srrna基因进行测序，测定了26个抗生素耐药基因的相对丰度、肠杆菌科对四环素和磺胺类抗生素的耐药比例以及微生物群的分类组成。改变试剂盒周围的微生物可能会阻碍抗生素耐药基因在一代人之间的传播，但这三个群体对肠道微生物的定位能力和对抗生素耐药基因的影响存在很大差异。微生物群落的最有效投递使肠道耐药菌的比例由93%降低到9%，降低了8种抗生素耐药基因的相对丰度，并在断奶时改变了试剂盒的肠道微生物。最低效率没有降低任何ARG或改变细菌群落。此外，添加粪便颗粒物比口服这些粪便颗粒物产生的厌氧悬浮液更有效。然而，我们无法预测从捐赠者数据中排除的结果（抗生素耐药基因的种类组成和丰度）。总之，我们揭示了微生物群落在排除抗生素抗性基因的能力方面的主要差异，但还需要更多的工作来了解导致抗生素抗性基因成功地从肠道中排除的成分。因此，关于竞争排斥的影响的研究应该使用几种微生物群落，以便得出一般性结论。

       Reducing antibiotic use is a necessary step toward less antibiotic resistance in livestock, but many antibiotic resistance genes can persist for years, even in an antibiotic-free environment. In this study, we investigated the potential of three fecal complex microbial communities from antibiotic-naive does to drive the microbiota of kits from antibiotic-exposed dams and outcompete bacteria-carrying antibiotic-resistant genes. The fecal complex microbial communities were either orally delivered or simply added as fresh fecal pellets in four to five nests that were kept clean from maternal feces. Additionally, four nests were cleaned for the maternal feces and five nests were handled according to the common farm practice (i.e., cleaning once a week) as controls. At weaning, we measured the relative abundance of 26 antibiotic resistance genes, the proportion of Enterobacteriaceae resistant to tetracycline and sulfonamide antibiotics, and the taxonomic composition of the microbiota by sequencing the 16S rRNA genes of one kit per nest. Changing the surrounding microbes of the kits can hinder the transmission of antibiotic resistance genes from one generation to the next, but the three communities widely differed in their ability to orient gut microbes and in their impact on antibiotic resistance genes. The most efficient delivery of the microbial community reduced the proportion of resistant Enterobacteria from 93 to 9%, decreased the relative abundance of eight antibiotic resistance genes, and changed the gut microbes of the kits at weaning. The least efficient did not reduce any ARG or modify the bacterial community. In addition, adding fecal pellets was more efficient than the oral inoculation of the anaerobic suspension derived from these fecal pellets. However, we were unable to predict the outcome of the exclusion from the data of the donor does (species composition and abundance of antibiotic resistance genes). In conclusion, we revealed major differences between microbial communities regarding their ability to exclude antibiotic resistance genes, but more work is needed to understand the components leading to the successful exclusion of antibiotic resistance genes from the gut. As a consequence, studies about the impact of competitive exclusion should use several microbial communities in order to draw general conclusions.

       https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6615258/