摘要

       畜牧业使用抗菌素会导致未代谢的抗菌素和抗菌素耐药基因 (ARG) 释放到环境中。然而，抗生素使用、残留抗生素和粪便中 ARG 流行率之间的关系尚不清楚，特别是在基于时间和位置的尺度上。目前的研究确定了来自美国东北部 11 个传统奶牛场和 1 个无抗菌素奶牛场的未经处理的粪便混合坑和长期储存系统中的 ARG 丰度，在一年内六次。使用自定义 qPCR 阵列或靶向 qPCR 对与四环素、大环内酯类-林可酰胺、磺胺类、氨基糖苷类和 β-内酰胺类耐药机制相对应的 13 个 ARG 进行量化。不同地点的 ARG 丰度不同，表明存在农场特定的微生物抗性组。 ARG 丰度也随时间变化。冬季收集的粪便含有较低的 ARG 丰度。总体而言，标准化的 ARG 浓度与农场和收集日期的平均抗菌素使用量或四环素浓度无关。在分析的 13 个 ARG 中，只有 4 个基因在来自常规农场的样本中显示出更高的丰度，而 8 个 ARG 在常规农场样本和不含抗生素的农场样本中表现出相似的标准化浓度。在从混合坑获得的乳制品粪便和在两个下降期（秋季和春季）收集的长期储存之间，没有观察到明显的 ARG 丰度趋势，尽管与秋季相比，春季通常观察到更高的 ARG 丰度。这项综合研究为确定来自乳制品粪便的 ARG 对环境的贡献所需的未来研究提供了信息。

       The use of antibiotics in the livestock industry can cause unmetabolized antibiotics and antimicrobial resistance genes (ARG) to be released into the environment. However, the relationship between antibiotic use, residual antibiotics, and the prevalence of ARG in feces is unclear, especially on a time- and location-based scale. The current study determined the abundance of ARG in untreated manure mixing pits and long-term storage systems from 11 traditional dairy farms and one antibiotic-free dairy farm in the northeastern United States, six times in a year. Use custom qPCR arrays or targeted qPCR to quantify 13 ARGs corresponding to tetracycline, macrolide-lincosamide, sulfonamides, aminoglycosides, and β-lactam resistance mechanisms. The abundance of ARG in different locations is different, indicating the existence of farm-specific microbial resistance groups. ARG abundance also changes over time. Feces collected in winter contain low ARG abundance. In general, the standardized ARG concentration has nothing to do with the average antibiotic usage or tetracycline concentration on the farm and the date of collection. Of the 13 ARGs analyzed, only 4 genes showed higher abundance in samples from conventional farms, while 8 ARGs showed similar normalized concentrations in samples from conventional farms and farm samples without antibiotics. No significant trend in ARG abundance was observed between the dairy manure obtained from the mixing pit and the long-term storage collected during the two decline periods (autumn and spring), although higher abundances were generally observed in spring compared to autumn ARG abundance. This comprehensive study provides information for future research needed to determine the environmental contribution of ARG from dairy manure.

https://pubs.acs.org/doi/abs/10.1021/acs.est.8b05702