Troiano Eleonora, Beneduce Luciano, Gross Amit, Ronen Zeev
Department of the Sciences of Agriculture, Food and Environment, University of Foggia, Foggia, Italy.
Department of Environmental Hydrology and Microbiology, Zuckerberg Institute for Water Research, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel.
Front Microbiol. 2018 Nov 6;9:2666. doi: 10.3389/fmicb.2018.02666. eCollection 2018.
This study represents the first systematic attempt to evaluate antibiotic-resistant bacteria (ARB) occurrence in treated greywater and the potential spread of these bacteria from the greywater to greywater-irrigated soil. Treated greywater from three recirculating vertical flow constructed wetlands, each located in a household in the central Negev Desert, Israel, was surveyed. The presence of antibiotic-resistant bacteria in raw and treated greywater was investigated with culture and molecular methods, as well as their presence in the corresponding treated-greywater-irrigated soils. Additionally, the effectiveness of chlorination to prevent the spread of ARB was tested. The total count of tetracycline-resistant bacteria significantly increased in the treated greywater, likely due to their concentration on the filter matrix of the treatment systems. Twenty-four strains of tetracycline-resistant bacteria were isolated and identified at the genus level by 16Sr RNA gene sequencing. All the tetracycline-resistant bacteria showed high resistance traits, and some of them presented multiple antibiotic resistances. Six tetracycline resistance genes (coding for efflux and ribosomal resistance mechanisms) and five β-lactamase genes were detected. In 14 of the isolated strains, the gene 39, which is phylogenetically related to both environmental and clinical strains, was identified. All the 39 resistant bacteria were positive to at least one of the β-lactamase genes tested. Chlorination was found to be an efficient method to reduce ARB in treated greywater. We concluded that disinfection of treated greywater may reduce the risks not only from the potential presence of pathogens but also from the presence of ARB and antibiotic resistance genes.
本研究首次系统地评估了经处理的中水（再生水）中抗生素抗性细菌（ARB）的出现情况，以及这些细菌从中水向中水灌溉土壤的潜在传播。对以色列内盖夫沙漠中部三个家庭中各自的循环垂直流人工湿地处理后的中水进行了调查。采用培养和分子方法研究了原水和处理后中水中抗生素抗性细菌的存在情况，以及它们在相应的经处理中水灌溉土壤中的存在情况。此外，还测试了氯化消毒对防止ARB传播的有效性。处理后的中水中四环素抗性细菌的总数显著增加，这可能是由于它们在处理系统的过滤基质上富集。通过16SrRNA基因测序在属水平上分离并鉴定了24株四环素抗性细菌。所有四环素抗性细菌均表现出高抗性特征，其中一些呈现多重抗生素抗性。检测到六个四环素抗性基因（编码外排和核糖体抗性机制）和五个β-内酰胺酶基因。在14株分离菌株中，鉴定出与环境菌株和临床菌株在系统发育上相关的基因39。所有39株抗性细菌对至少一种测试的β-内酰胺酶基因呈阳性。发现氯化消毒是减少处理后中水中ARB的有效方法。我们得出结论，处理后中水的消毒不仅可以降低病原体潜在存在带来的风险，还可以降低ARB和抗生素抗性基因存在带来的风险。
