NERC Centre for Ecology & Hydrology, Benson Lane, Wallingford, United Kingdom.
Environmental Diagnosis and Management, Royal Holloway University of London, Egham, United Kingdom.
PLoS One. 2019 Sep 4;14(9):e0221568. doi: 10.1371/journal.pone.0221568. eCollection 2019.
The environment receives antibiotics through a combination of direct application (e.g., aquaculture and fruit production), as well as indirect release through pharmaceutical manufacturing, sewage and animal manure. Antibiotic concentrations in many sewage-impacted rivers are thought to be sufficient to select for antibiotic resistance genes. Yet, because antibiotics are nearly always found associated with antibiotic-resistant faecal bacteria in wastewater, it is difficult to distinguish the selective role of effluent antibiotics within a 'sea' of gut-derived resistance genes. Here we examine the potential for macrolide and fluoroquinolone prescribing in England to select for resistance in the River Thames catchment, England. We show that 64% and 74% of the length of the modelled catchment is chronically exposed to putative resistance-selecting concentrations (PNEC) of macrolides and fluoroquinolones, respectively. Under current macrolide usage, 115 km of the modelled River Thames catchment (8% of total length) exceeds the PNEC by 5-fold. Similarly, under current fluoroquinolone usage, 223 km of the modelled River Thames catchment (16% of total length) exceeds the PNEC by 5-fold. Our results reveal that if reduced prescribing was the sole mitigating measure, that macrolide and fluoroquinolone prescribing would need to decline by 77% and 85%, respectively, to limit resistance selection in the catchment. Significant reductions in antibiotic prescribing are feasible, but innovation in sewage-treatment will be necessary for achieving substantially-reduced antibiotic loads and inactivation of DNA-pollution from resistant bacteria. Greater confidence is needed in current risk-based targets for antibiotics, particularly in mixtures, to better inform environmental risk assessments and mitigation.
环境通过直接应用（例如水产养殖和水果生产）以及通过制药制造、污水和动物粪便的间接释放接收抗生素。许多受污水影响的河流中的抗生素浓度被认为足以选择抗生素抗性基因。然而，由于抗生素几乎总是与废水中的抗生素抗性粪便细菌相关联，因此很难在“肠道”来源的抗性基因的“海洋”中区分流出物抗生素的选择作用。在这里，我们研究了英格兰大环内酯类和氟喹诺酮类药物的处方在英格兰泰晤士河流域选择耐药性的潜力。我们表明，模型流域的 64%和 74%的长度分别长期暴露于大环内酯类和氟喹诺酮类药物的假定抗性选择浓度（PNEC）下。在当前大环内酯类药物的使用下，模型泰晤士河流域的 115 公里（总长度的 8%）超过了 PNEC 的 5 倍。同样，在当前氟喹诺酮类药物的使用下，模型泰晤士河流域的 223 公里（总长度的 16%）超过了 PNEC 的 5 倍。我们的结果表明，如果减少处方是唯一的缓解措施，那么大环内酯类和氟喹诺酮类药物的处方需要分别下降 77%和 85%，以限制流域内的耐药性选择。抗生素处方的大幅减少是可行的，但需要在污水处理方面进行创新，以减少抗生素负荷并灭活来自耐药细菌的 DNA 污染。需要对当前基于风险的抗生素目标（尤其是混合物）有更大的信心，以更好地为环境风险评估和缓解提供信息。
