Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
Proc Natl Acad Sci U S A. 2013 Feb 26;110(9):3435-40. doi: 10.1073/pnas.1222743110. Epub 2013 Feb 11.
Antibiotic resistance genes (ARGs) are emerging contaminants posing a potential worldwide human health risk. Intensive animal husbandry is believed to be a major contributor to the increased environmental burden of ARGs. Despite the volume of antibiotics used in China, little information is available regarding the corresponding ARGs associated with animal farms. We assessed type and concentrations of ARGs at three stages of manure processing to land disposal at three large-scale (10,000 animals per year) commercial swine farms in China. In-feed or therapeutic antibiotics used on these farms include all major classes of antibiotics except vancomycins. High-capacity quantitative PCR arrays detected 149 unique resistance genes among all of the farm samples, the top 63 ARGs being enriched 192-fold (median) up to 28,000-fold (maximum) compared with their respective antibiotic-free manure or soil controls. Antibiotics and heavy metals used as feed supplements were elevated in the manures, suggesting the potential for coselection of resistance traits. The potential for horizontal transfer of ARGs because of transposon-specific ARGs is implicated by the enrichment of transposases--the top six alleles being enriched 189-fold (median) up to 90,000-fold in manure--as well as the high correlation (r(2) = 0.96) between ARG and transposase abundance. In addition, abundance of ARGs correlated directly with antibiotic and metal concentrations, indicating their importance in selection of resistance genes. Diverse, abundant, and potentially mobile ARGs in farm samples suggest that unmonitored use of antibiotics and metals is causing the emergence and release of ARGs to the environment.
抗生素耐药基因（ARGs）是新兴的污染物，对全球人类健康构成潜在威胁。集约化畜牧业被认为是导致 ARGs 环境负担增加的主要因素。尽管中国使用了大量的抗生素，但有关与养殖场相关的相应 ARGs 的信息却很少。我们评估了在中国三个大型（每年 10000 头动物）商业养猪场的粪便处理过程中的三个阶段的 ARGs 类型和浓度。这些农场使用的饲料或治疗性抗生素包括除万古霉素以外的所有主要抗生素类别。高通量定量 PCR 阵列在所有农场样本中检测到 149 种独特的耐药基因，其中前 63 种 ARGs 的丰度比相应的无抗生素粪便或土壤对照分别富集了 192 倍（中位数）至 28000 倍（最大值）。作为饲料添加剂使用的抗生素和重金属在粪便中含量升高，表明存在耐药特性的共选择。由于转座子特异性 ARGs 的存在，转座酶的富集暗示了 ARGs 水平转移的可能性——前六种等位基因在粪便中的富集度为 189 倍（中位数）至 90000 倍——以及 ARG 和转座酶丰度之间的高度相关性（r(2) = 0.96）。此外，ARGs 的丰度与抗生素和金属浓度直接相关，表明它们在耐药基因的选择中具有重要作用。农场样本中多样化、丰富且具有潜在迁移能力的 ARGs 表明，未经监测的抗生素和金属的使用正在导致 ARGs 的出现和释放到环境中。
