Centre for Antibiotic Resistance Research (CARe) at the University of Gothenburg, Guldhedsgatan 10A, 413 46 Gothenburg, Sweden; Department of Infectious Diseases, Institute of Biomedicine, The Sahlgrenska Academy at the University of Gothenburg, Guldhedsgatan 10A, 413 46 Gothenburg, Sweden.
Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark; Sino-Danish Center for Education and Research (SDC), University of Chinese Academy of Sciences, 380 Huaibeizhuang, Beijing, China.
Environ Int. 2020 Apr;137:105339. doi: 10.1016/j.envint.2019.105339. Epub 2020 Feb 6.
The widespread practice of applying sewage sludge to arable land makes use of nutrients indispensable for crops and reduces the need for inorganic fertilizer, however this application also provides a potential route for human exposure to chemical contaminants and microbial pathogens in the sludge. A recent concern is that such practice could promote environmental selection and dissemination of antibiotic resistant bacteria or resistance genes. Understanding the risks of sludge amendment in relation to antibiotic resistance development is important for sustainable agriculture, waste treatment and infectious disease management. To assess such risks, we took advantage of an agricultural field trial in southern Sweden, where land used for growing different crops has been amended with sludge every four years since 1981. We sampled raw, semi-digested and digested and stored sludge together with soils from the experimental plots before and two weeks after the most recent amendment in 2017. Levels of selected antimicrobials and bioavailable metals were determined and microbial effects were evaluated using both culture-independent metagenome sequencing and conventional culturing. Antimicrobials or bioavailable metals (Cu and Zn) did not accumulate to levels of concern for environmental selection of antibiotic resistance, and no coherent signs, neither on short or long time scales, of enrichment of antibiotic-resistant bacteria or resistance genes were found in soils amended with digested and stored sewage sludge in doses up to 12 metric tons per hectare. Likewise, only very few and slight differences in microbial community composition were observed after sludge amendment. Taken together, the current study does not indicate risks of sludge amendment related to antibiotic resistance development under the given conditions. Extrapolations should however be done with care as sludge quality and application practices vary between regions. Hence, the antibiotic concentrations and resistance load of the sludge are likely to be higher in regions with larger antibiotic consumption and resistance burden than Sweden.
将污水污泥施用于耕地是一种广泛的做法，它利用了作物不可或缺的养分，减少了对无机肥料的需求，但这种做法也为人类接触污泥中的化学污染物和微生物病原体提供了潜在途径。最近人们关注的一个问题是，这种做法可能会促进环境选择和传播抗生素耐药细菌或耐药基因。了解污泥改良与抗生素耐药性发展相关的风险对于可持续农业、废物处理和传染病管理非常重要。为了评估这些风险，我们利用了瑞典南部的一个农业田间试验，自 1981 年以来，每年都会用污泥改良用于种植不同作物的土地。我们在 2017 年最近一次施肥前和施肥后两周，从实验地块采集了未经处理、半消化和消化并储存的污泥以及土壤样本。我们测定了选定的抗生素和生物可利用金属的水平，并使用非培养宏基因组测序和传统培养方法评估了微生物的影响。抗生素或生物可利用金属（铜和锌）没有积累到引起环境选择抗生素耐药性的水平，并且在高达 12 吨/公顷的剂量下，用消化并储存的污水污泥改良的土壤中，无论是短期还是长期，都没有发现抗生素耐药细菌或耐药基因富集的明显迹象。同样，在污泥改良后，仅观察到微生物群落组成的非常少和轻微差异。总的来说，在给定条件下，当前的研究并没有表明污泥改良与抗生素耐药性发展相关的风险。然而，由于污泥质量和应用实践在不同地区存在差异，因此应该谨慎推断。因此，与瑞典相比，在抗生素使用量和耐药负担较大的地区，污泥中的抗生素浓度和耐药负荷可能更高。
