December 17, 2019 by Grace Panter

In November, Grace Panter attended the Water Science Forum conference on “Antibiotics in the Water Environment: Occurrence, Detection and Fate”, in London, UK. The aim was to understand the significance and extent of antibiotic pollution through its impact on freshwater ecology, wastewater treatment and likely contribution to antibiotic resistance.

The scale of pharmaceutical contaminants in rivers, including antibiotics, is becoming more widely understood, thanks to a global monitoring project led by University of York. The highest concentrations of antibiotics were found in low-middle income countries, where they were available but there is no/ limited wastewater treatment infrastructure. Key environmental sources of antibiotics comprise domestic wastewater, hospitals, manufacturing sites, animal manure, aquaculture and composting.

Antimicrobial resistance (AMR) is of increasing concern. William Gaze (University of Exeter), discussed the need for more models to predict the emergence/ evolution of AMR and to understand the acute risk of environmental transmissions. Work from a PhD project, with the Centre of Ecology and Hydrology, on resistance of Aspergillus fumigatus to antibiotics had demonstrated that spores collected on windowsills primarily in the UK, had an overall resistance of 4.7% to azole fungicides and that the degree of resistance varies depending of the time of year. Future work is planned to develop a hazard map and to assess soil samples. In a presentation by Barbara Kasprzyk-Horden (University of Bath), population size and antibiotic daily load, rather than environmental concentrations, show the best correlation to presence of AMR genes. Stereochemistry may also be key to understanding the mechanisms behind AMR, with microbes having a preference to degrade one isomer over another, or one isomer being more toxic to bacteria.

The ability of wastewater treatment processes to remove antibiotics and the production of AMR genes with wastewater treatment works featured heavily in the meeting. UK Water Industry Research (UKWIR) has included an extensive AMR element in Phase III of its national Chemicals Investigation Programme (CIP), in which they will investigate 10 wastewater treatment plants and 5 sludges to understand the prevalence, source and variation of AMR in effluent and sludge. The programme also aims to improve our understanding of the contribution from the water industry to the spread of AMR and ways to improve the processes. Technologies that reduce non-flocculating bacteria are thought to be the best for reducing AMR genes coming out of wastewater treatment plants, with biosolid separation and removal of non-flocculating bacteria being key processes for AMR removal.

Jan-Ulrich Kreft (Birmingham University) presented on the influence of wastewater treatment plants on AMR and found a lack of evidence that AMR increases in the treatment plants due to selection, with relative abundance being the same in the influent and effluent. However, there is the potential for transfer of resistant genes via plasmids, and this research group have developed a simple plasmid model to investigate this.

In 2016, Becky Brown, blogged on the growing global concerns regarding AMR and the need for antibiotic environmental risk assessments to consider their effects on microbial communities and selection for AMR. Environmental risk assessments could make better use of currently available standard test methods and at wca we could provide support in tailoring your environmental risk assessment for these substances.