Evolution and selection of resistant bacteria in the presence of subinhibitory concentrations of micropollutants

微污染物亚抑制浓度下耐药细菌的进化和选择

• 批准号: 462477863
• 负责人: Professorin Dr. Gabriele Bierbaum
• 金额: --
• 依托单位: Institut für Medizinische Mikrobiologie, Immunologie und Parasitologie
• 依托单位国家: 德国
• 项目类别: Research Units
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/462477863?language=en
• 关键词: Evolution; selection; resistant; bacteria; presence

The use of wastewater for irrigation of agricultural land optimizes the efficient use of scarce water resources and the production of food under conditions of climate change. Wastewater is increasingly treated prior to its use in agriculture in order to minimize health risks, with the Mezquital Valley, Mexico, representing an important model case. The central hypothesis of the research unit FOR 5095 is that hitherto unforeseen risks arise from the implementation of wastewater treatment in long-established wastewater irrigation systems, due to i) the release of pollutants that have formerly been accumulated in soils, leading to ii) concentrations that (co-)select for antimicrobial resistance with iii) release and concentrations of antibiotics as well as selection of antibiotic resistance depending on soil type. SP 3 will contribute to testing these hypotheses by characterizing the selection pressure exerted by single antibiotics (ciprofloxacin, several MLSB antibiotics, sulfamethoxazole, trimethoprim) and disinfectants (quaternary alkylammonium compounds) as well as by their combinations in competition experiments employing strain pairs with different susceptibilities. These completion experiments will be conducted in nutrient broth solutions as well as in filtered aqueous extracts of Mexican soils (Leptosols, Phaeozems and Vertisols), in order to assess the influence of suspended colloids and solutes on the selection effects of antibiotics and biocides (collaboration with SP 1). We will use existing Acinetobacter baylyi strain pairs as well as other strain pairs (Escherichia coli, Enterococcus faecium) harboring plasmids that are isolated from Mexican soil and wastewater by SP 4 and SP 5 for the competition experiments. Employing these strain pairs, the minimum antibiotic/biocide concentrations that give selection advantages to the resistant strains will be determined and integrated into the mathematical model of the fate and effects of antibiotics and disinfectants developed by SP 7. Transcriptome experiments will give information about the stress responses of the bacteria. Screening for resistant mutants and their subsequent sequencing will show whether the presence of antibiotics in the extracts leads to selection of bacteria harboring mutations that confer resistance. The antibiograms of facultative pathogenic bacteria, that are isolated during the joint experiments from Mexican soil and wastewater by SP 4, SP 5, and SP 6, will show whether bacteria with clinically relevant multi-resistance phenotypes or plasmids that confer resistance to relevant antibiotics like beta-lactams (e.g., carbapenems) or antibiotics of last resort (e.g., colistin), are enriched in soils with a higher availability of free antibiotics or are even present on fresh produce grown on these soils. In this way, SP 3 contributes to a mechanistic understanding of interactions between pollutants, antibiotic resistance and pathogens in changing wastewater irrigation systems.

在气候变化的条件下，利用废水灌溉农地，最大限度地有效利用稀缺的水资源和粮食生产。越来越多的废水在用于农业之前进行处理，以最大限度地减少健康风险，墨西哥的梅兹奎特山谷就是一个重要的示范案例。研究单位对5095的中心假设是，在建立已久的污水灌溉系统中实施废水处理会产生迄今无法预见的风险，原因是：1)以前在土壤中积累的污染物的释放，导致2)与抗菌剂耐药性共同选择的浓度；3)抗生素的释放和浓度，以及根据土壤类型选择抗生素耐药性。SP 3将通过表征单一抗生素(环丙沙星、几种MLSB抗生素、磺胺甲恶唑、甲氧嘧啶)和消毒剂(季铵盐化合物)以及它们的组合在使用不同敏感性的菌株对的竞争实验中施加的选择压力，有助于检验这些假说。这些完井实验将在营养肉汤溶液以及墨西哥土壤的过滤水萃取物(Leptosol、Phaeozems和Vertisols)中进行，以评估悬浮胶体和溶质对抗生素和杀生剂选择效果的影响(与SP 1合作)。我们将使用现有的贝利不动杆菌菌株对以及其他含有由SP 4和SP 5从墨西哥土壤和废水中分离出的质粒的菌株对(大肠杆菌、粪肠球菌)进行竞争实验。利用这些菌株对，将确定使耐药菌株具有选择优势的最低抗生素/杀生剂浓度，并将其整合到SP 7开发的抗生素和消毒剂命运和影响的数学模型中。转录组实验将提供有关细菌应激反应的信息。对耐药突变的筛选和随后的测序将表明，提取物中是否存在抗生素，是否会导致选择含有突变的细菌。在SP4、SP5和SP6的联合实验中从墨西哥土壤和废水中分离出的兼性致病菌的抗生素图谱将显示，具有临床相关多重耐药表型或对相关抗生素(如β-内酰胺类(例如碳青霉烯类)或最后手段抗生素(如粘菌素))产生抗药性的质粒的细菌是否在游离抗生素可获得性较高的土壤中丰富，或者甚至在这些土壤上种植的新鲜农产品中存在。通过这种方式，SP3有助于在不断变化的污水灌溉系统中从机理上理解污染物、抗生素耐药性和病原体之间的相互作用。