城镇污水厂中超广谱β-内酰胺酶和碳青霉烯酶基因的污染特征、水平转移和环境健康风险研究

Antibiotic resistance has become one of the world's largest public health threats in the 21st century. The environment is an important place for the generation and spread of emerging antibiotic-resistant pollutants. There is an urgent need for comprehensive health risk assessment of different types of antibiotic resistance genes (ARGs) found in the environment to block the transmission of high-risk ARGs and their hosts from the environment to the human body, thereby maximizing the lifespan of antibiotic as a valuable human resource. Domestic and foreign scholars have carried out extensive investigations on the spatial and temporal diversity of ARGs in the environment, but the environmental host characteristics (e.g., pathogenicity and multi-resistance) and horizontal transferability of such emerging pollutants have received less attention. In particular, there is currently a lack of methods for assessing the health risks of key medical antibiotic-resistant contaminants such as extended-spectrum β-lactamases (ESBLs) and carbapenemases in the environmental samples (e.g., wastewater). Based on metagenomics and bioinformatics, this project is to develop new metrics and models that can quantitatively assess the health risks of environmentally found ARGs, and apply them to predict the comprehensive environmental health risks of resistant pollutants of key clinically-used antibiotics in urban sewage, including ESBL and carbapenemase-coding genes. The project outcomes will provide new methods and tools for global environmental risk assessment of ARGs, providing guidance for the subsequent monitoring and control of necessary antibiotic resistant pollutants.

抗生素抗性已经成为21世纪全球最大公共卫生安全威胁之一。环境是抗生素抗性污染产生和传播的重要场所，迫切需要评估环境中抗生素抗性基因（ARGs）的健康风险，并阻断高健康风险ARGs及其宿主从环境向人体的传播，进而最大限度地延长抗生素作为人类宝贵资源的使用寿命。国内外学者围绕ARGs在环境中的时空多样性开展了广泛调查；然而，这类新兴环境污染物的宿主特性（如致病性、多重抗性）和水平转移能力却较少受到关注，极大限制了对ARGs健康风险的客观认识。特别地，还缺乏污水中超广谱β-内酰胺酶（ESBLs）和碳青霉烯酶这类关键医用抗生素抗性污染的健康风险评价方法。本项目将基于宏基因组测序和生物信息学开发可定量评估环境ARGs健康风险的新指标和模型，并应用其预测污水中ESBLs和碳青霉烯酶基因的健康风险。项目成果将为全球环境ARG风险评估提供新方法和新工具，为后续开展必要的抗生素抗性污染物监测和管控提供指导。

抗生素抗性是21世纪全球最大公共卫生安全威胁之一。抗生素抗性基因（ARGs）被认为是一种全球新兴污染物，环境是其污染产生和传播的重要场所。城镇污水处理厂是ARGs的汇与源。尽管国内外学者围绕ARGs在环境中的时空多样性与丰度等基本特征开展了广泛调查；然而，ARGs传播能力与宿主细菌身份、致病性和功能活性等等核心特征不明，极大限制了对于当前环境耐药组的健康风险的评估能力与客观认知水平。特别地，还缺乏污水中超广谱β-内酰胺酶（ESBLs）和碳青霉烯酶这类关键医用抗生素抗性污染的健康风险评价方法。该项目研究解析了污水厂中抗性基因宿主细菌的身份、分布、活性、功能等关键污染特征信息，揭示了污水处理过程中抗生素抗性和脱氮功能的交互作用。研究指出，污水处理的微生物群落中的病原菌和土著反硝化菌是抗性基因的主要宿主，且在污水处理过程中并未被完全去除。因此应对已处理的出水谨慎处置以免带来安全风险。在此基础上，研究组还首次提出了“表型宏基因组学”(Phenotypic Metagenomics) 新概念及基于富集培养的方法学框架，并率先应用于城市污水厂和受纳河流中超广谱β-内酰胺酶和碳青霉烯酶基因的污染特征解析与宿主细菌检测，阐释了其发生水平转移传播的潜力与环境健康风险。该方法整合了环境微生物组的选择性培养富集、靶标抗性表型筛选和宏基因组深度测序与分析，以探索碳青霉烯类和超广谱头孢菌素类抗性基因的遗传特征及其宿主的分类学特征、致病性和耐药图谱，有望发展为环境中靶标耐药组的标准化监测方法。综上，本项目开发了环境中临床相关ARGs的高通量检测的新方法与健康风险评价的新指标，并应用其评估了污水厂ESBLs和碳青霉烯酶基因的健康风险。该成果将为全球环境ARG风险评估提供新方法和新工具，为后续开展必要的抗生素抗性污染物监测和管控提供指导。