Universidad Nacional Autónoma de México, Instituto de Geología, Ciudad Universitaria, Mexico City, Mexico.
Universidad Nacional Autónoma de México, Instituto de Geología, Ciudad Universitaria, Mexico City, Mexico.
Chemosphere. 2018 Feb;193:1198-1206. doi: 10.1016/j.chemosphere.2017.11.143. Epub 2017 Nov 24.
Antibiotic resistance genes in soil pose a potential risk for human health. They can enter the soil by irrigation with untreated or insufficiently treated waste water. We hypothesized that water flow paths trigger the formation of antibiotic resistance, since they transport antibiotics, multi-resistant bacteria and free resistance genes through the soil. To test this, we irrigated soil cores once or twice with waste water only, or with waste water added with sulfamethoxazole (SMX) and ciprofloxacin (CIP). The treatments also contained a dye to stain the water flow paths and allowed to sample these separately from unstained bulk soil. The fate of SMX and CIP was assessed by sorption experiments, leachate analyses and the quantification of total and extractable SMX and CIP in soil. The abundance of resistance genes to SMX (sul1 and sul2) and to CIP (qnrB and qnrS) was quantified by qPCR. The sorption of CIP was larger than the dye and SMX. Ciprofloxacin accumulated exclusively in the water flow paths but the resistance genes qnrB and qnrS were not detectable. The SMX concentration in the water flow paths doubled the concentration of the bulk soil, as did the abundance of sul genes, particularly sul1 gene. These results suggest that flow paths do function as hotspots for the accumulation of antibiotics and trigger the formation of resistance genes in soil. Their dissemination also depends on the mobility of the antibiotic, which was much larger for SMX than for CIP.
土壤中的抗生素耐药基因对人类健康构成潜在威胁。它们可以通过灌溉未经处理或处理不充分的废水进入土壤。我们假设水流路径会引发抗生素耐药性的形成，因为它们通过土壤运输抗生素、多耐药细菌和游离耐药基因。为了验证这一点，我们只用废水或添加磺胺甲恶唑 (SMX) 和环丙沙星 (CIP) 的废水对土壤芯进行了一次或两次灌溉。这些处理还添加了一种染料来染色水流路径，并允许从未染色的散装土壤中单独采样这些路径。通过吸附实验、淋出液分析和土壤中总可提取 SMX 和 CIP 的定量来评估 SMX 和 CIP 的命运。通过 qPCR 定量了对 SMX（sul1 和 sul2）和 CIP（qnrB 和 qnrS）的耐药基因的丰度。CIP 的吸附量大于染料和 SMX。环丙沙星仅在水流路径中积累，但 qnrB 和 qnrS 等耐药基因无法检测到。水流路径中的 SMX 浓度是散装土壤的两倍，sul 基因的丰度也是如此，尤其是 sul1 基因。这些结果表明，水流路径确实是抗生素积累和土壤中耐药基因形成的热点。它们的传播也取决于抗生素的迁移性，SMX 的迁移性比 CIP 大得多。
