Department of Chemistry , University at Buffalo, The State University of New York (SUNY) , Buffalo , New York 14260 , United States.
Department of Animal Sciences , Cornell University , Ithaca , New York 14850 , United States.
Environ Sci Technol. 2019 Mar 5;53(5):2405-2415. doi: 10.1021/acs.est.8b05702. Epub 2019 Feb 15.
The use of antimicrobials by the livestock industry can lead to the release of unmetabolized antimicrobials and antimicrobial resistance genes (ARG) into the environment. However, the relationship between antimicrobial use, residual antimicrobials, and ARG prevalence within manure is not well understood, specifically across temporal and location-based scales. The current study determined ARG abundance in untreated manure blend pits and long-term storage systems from 11 conventional and one antimicrobial-free dairy farms in the Northeastern U.S. at six times over one-year. Thirteen ARGs corresponding to resistance mechanisms for tetracyclines, macrolides-lincosamides, sulfonamides, aminoglycosides, and β-lactams were quantified using a Custom qPCR Array or targeted qPCR. ARG abundance differed between locations, suggesting farm specific microbial resistomes. ARG abundance also varied temporally. Manure collected during the winter contained lower ARG abundances. Overall, normalized ARG concentrations did not correlate to average antimicrobial usage or tetracycline concentrations across farms and collection dates. Of the 13 ARGs analyzed, only four genes showed a higher abundance in samples from conventional farms and eight ARGs exhibited similar normalized concentrations in the conventional and antimicrobial-free farm samples. No clear trends were observed in ARG abundance between dairy manure obtained from blend pits and long-term storage collected during two drawdown periods (fall and spring), although higher ARG abundances were generally observed in spring compared to fall. This comprehensive study informs future studies needed to determine the contributions of ARGs from dairy manure to the environment.
畜牧业对抗生素的使用会导致未代谢的抗生素和抗生素耐药基因（ARG）释放到环境中。然而，抗生素的使用、粪便中残留的抗生素和 ARG 流行率之间的关系在时间和地理位置上的关系还不是很清楚。本研究在一年内六次测定了来自美国东北部 11 个常规和一个无抗生素的奶牛场未经处理的粪肥混合坑和长期储存系统中的 ARG 丰度。使用定制 qPCR 阵列或靶向 qPCR 定量了与四环素、大环内酯-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。ARG 丰度因地点而异，表明存在特定于农场的微生物耐药组。ARG 丰度也随时间变化而变化。冬季采集的粪便中 ARG 丰度较低。总体而言，标准化的 ARG 浓度与农场和采集日期的平均抗生素使用量或四环素浓度无关。在所分析的 13 个 ARG 中，只有 4 个基因在常规农场的样本中丰度更高，而 8 个 ARG 在常规和无抗生素农场的样本中表现出相似的标准化浓度。虽然春季的 ARG 丰度通常高于秋季，但在从混合坑中获得的奶牛粪肥和在两个排水期（秋季和春季）收集的长期储存中，ARG 丰度之间没有明显的趋势。这项全面的研究为未来的研究提供了信息，需要确定奶牛粪肥中 ARG 对环境的贡献。
