摘要

       我们确定了接触抗生素治疗动物对土壤微生物组和抵抗组的直接影响。收集来自用或不用氟苯尼考处理 30 天以上的奶牛犊 (n = 6) 的粪便 (n = 36) 和土壤 (n = 108) 样品。通过香农多样性（16S rRNA 基因测序；P = 0.03）测量，抗生素处理的小牛的肠道微生物组出现暂时性变化，但饲养土壤微生物组中没有（P > 0.05）。液滴数字 PCR 表明 floR 基因在暴露于处理过的动物的土壤中增加了 1-log（P < 0.001），但它在未用抗生素处理的小牛的对照土壤中保持相对稳定。暴露土壤中的抗性发生了很大变化（P = 0.004），抗菌素抗性基因（ARG）的总体流行率显着升高（第 10 天增加了 3.8 倍；P = 0.01）。除氟苯尼考外，富集的 ARG 共同赋予对四环素、氨基糖苷类、磺胺类、艾法霉素、大环内酯类-林可酰胺类-链霉蛋白 A/B 和 β-内酰胺类药物的抗性。定量 PCR 验证了在暴露于氟苯尼考处理的小牛的土壤中，包括 str 和 tetG 的 ARG 相对于对照土壤随着时间的推移逐渐增加了倍数变化差异。此外，在暴露的土壤中观察到更多多样性的可转移 ARGs，这些与更大的细菌物种多样性有关。在接触抗生素处理的动物后原位评估农场对土壤的影响可以帮助设计有效的管理，以减轻食用动物生产中的抗生素耐药性。

       We determined the immediate impact of exposure to antibiotic-treated animals on housing soil microbiome and resistome. Fecal (n = 36) and soil (n = 108) samples from dairy calves (n = 6) treated with and without florfenicol over 30 days were collected. There were temporary changes in the gut microbiome of antibiotic-treated calves as measured by Shannon diversity (16S rRNA gene sequencing; P = 0.03), but not in the housing soil microbiome (P > 0.05). Droplet-digital PCR demonstrated that floR gene increased by 1-log in soil exposed to treated animals (P < 0.001), but it remained relatively stable in the control soil whereby calves were not treated with antibiotic. Resistome in exposed soil was largely modified (P = 0.004) with the overall prevalence of antimicrobial resistance genes (ARGs) significantly elevated (3.8-fold increase by day 10; P = 0.01). In addition to florfenicol, enriched ARGs collectively conferring resistance to tetracyclines, aminoglycosides, sulfonamides, elfamycins, macrolides-lincosamides-streptrogramin A/B, and beta-lactams. Quantitative PCR validated that ARGs including str and tetG in soil exposed to florfenicol-treated calves had gradually increased fold-change difference relative to the control soil over time. Moreover, a greater diversity of transferrable ARGs was observed in exposed soil and these were associated with a greater diversity of bacterial species. Evaluation of on-farm effects to soil in situ after exposure to antibiotic-treated animals can help design effective managements to mitigate antibiotic resistance in food-animal production.

https://www.sciencedirect.com/science/article/abs/pii/S0048969720352232