Impact of Manure Fertilization on the Abundance of Antibiotic-Resistant Bacteria and Frequency of Detection of Antibiotic Resistance Genes in Soil and on Vegetables at Harvest
Impact of Manure Fertilization on the Abundance of Antibiotic-Resistant Bacteria and Frequency of Detection of Antibiotic Resistance Genes in Soil and on Vegetables at Harvest
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DOI：
10.1128/aem.01682-13
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发表时间：
2013-09-01
影响因子：
4.4
通讯作者：
Topp, Edward
中科院分区：
文献类型：
--
作者：
Marti, Romain;Scott, Andrew;Topp, Edward
食用蔬菜是人类直接接触土壤中细菌的一种途径。本研究评估了经常生吃的蔬菜（番茄、黄瓜、胡椒、胡萝卜、萝卜、生菜）上对各种抗生素具有抗药性的细菌的补充，以及这种补充如何随着无机施肥或乳制品或猪粪施肥的土壤中的生长而变化。蔬菜在施肥后立即播种到田间，并在达到上市质量时收获。通过在补充有临床断点浓度抗生素的 Chromocult 培养基上进行平板计数，评估蔬菜和土壤样品中活的抗生素抗性细菌。从土壤和蔬菜中提取 DNA，并通过 PCR 评估是否存在与质粒不相容性群体、整合子或抗生素抗性基因相关的 46 个基因靶标。接收粪便的土壤富含抗生素抗性细菌和各种抗生素抗性决定因素。在施肥土壤中种植的任何蔬菜中，抗生素抗性细菌的丰度并没有相应增加。从未施肥土壤中生长的蔬菜中提取的 DNA 中检测到了许多抗生素抗性决定因素。在仅在施肥土壤中而非未施肥土壤中生长的蔬菜中还检测到了少量决定因素。总体而言，生吃蔬菜是人类接触土壤中自然存在的抗生素抗性细菌和抗性决定因素的一种途径。然而，对仅在新鲜施肥的土壤中生长的蔬菜的一些决定因素的检测强化了通过堆肥或其他稳定过程来预处理粪便的可取性，或者强制施肥和收获蔬菜之间的偏移时间供人类食用。
Consumption of vegetables represents a route of direct human exposure to bacteria found in soil. The present study evaluated the complement of bacteria resistant to various antibiotics on vegetables often eaten raw (tomato, cucumber, pepper, carrot, radish, lettuce) and how this might vary with growth in soil fertilized inorganically or with dairy or swine manure. Vegetables were sown into field plots immediately following fertilization and harvested when of marketable quality. Vegetable and soil samples were evaluated for viable antibiotic-resistant bacteria by plate count on Chromocult medium supplemented with antibiotics at clinical breakpoint concentrations. DNA was extracted from soil and vegetables and evaluated by PCR for the presence of 46 gene targets associated with plasmid incompatibility groups, integrons, or antibiotic resistance genes. Soil receiving manure was enriched in antibiotic-resistant bacteria and various antibiotic resistance determinants. There was no coherent corresponding increase in the abundance of antibiotic-resistant bacteria enumerated from any vegetable grown in manure-fertilized soil. Numerous antibiotic resistance determinants were detected in DNA extracted from vegetables grown in unmanured soil. A smaller number of determinants were additionally detected on vegetables grown only in manured and not in unmanured soil. Overall, consumption of raw vegetables represents a route of human exposure to antibiotic-resistant bacteria and resistance determinants naturally present in soil. However, the detection of some determinants on vegetables grown only in freshly manured soil reinforces the advisability of pretreating manure through composting or other stabilization processes or mandating offset times between manuring and harvesting vegetables for human consumption.