Research 162 - Hospital effluent: impact on the microbial environment and risk to human health
Authors: Dearbháile Morris, Suvi Harris, Carol Morris, Enda Commins and Martin Cormican.
Summary: Antibiotic resistance is a major public health problem. In Ireland, and most of Europe, hospital effluent is released into the urban wastewater system without any specific measurement of antibiotic levels or antibiotic-resistant bacteria, and without any pre-treatment.
Antibiotic resistance is a major public health problem. In Ireland, and most of Europe, hospital effluent is released into the urban wastewater system without any specific measurement of antibiotic levels or antibiotic-resistant bacteria, and without any pre-treatment. There are concerns that the release of these contaminants into the urban wastewater may result in downstream exposure to antibiotics and contribute to the growing problem of antibiotic resistance. In this report, a three year study was undertaken to 1) quantify the impact of hospital discharge on the number of antibiotic resistant E.coli and concentration of antibiotics in urban waste water,2) estimate the survival of antibiotic resistant E. coli in each step of the waste water treatment process to discharge,3) estimate the persistence/removal of antibiotics in each step of the waste water treatment process to discharge,4) develop a risk assessment model of human exposure to antibiotics and antibiotic resistant E. coli in recreational water related to discharge in hospital effluent.
Identifying Pressures
This report demonstrates that there are high levels of antibiotic-resistant E. coli in urban wastewater, and dealing with hospital effluent in isolation will not substantially address the overall issue of antibiotic-resistant bacteria in urban wastewater. The report identifies that, at best, wastewater treatment plants (WWTPs) do not remove or inactivate all antibiotic-resistant bacteria and that further research is required to understand the processes underlying this and identify risk management strategies. This research also reveals that some antibiotics may persist in the environment for extended periods after discharge and that the predicted levels of antibiotics in the environment are such that they may plausibly contribute to the development and maintenance of antibiotic resistance.
Informing Policy
The research informs current policies on protection of public health from water borne contaminants and the necessity for development of additional indicators or monitoring strategies. The research builds capacity in the area of Environment and Health. The research is relevant in the context of the EU Water Framework Directive, the European Commission’s ‘A Blueprint to Safeguard Europe’s Water Resources’ and to the 7th EU Environment Action Programme which aims “to safeguard the Union’s citizens from environment-related pressures and risks to health and wellbeing”. The research also informs the following national regulations and EU directives, the EU Water Framework Directive, the Urban Wastewater Directive(1991); the Bathing Water Directive (2008); and the Drinking Water Directive (2014).
Developing Solutions
The research identifies that new antibiotics, such as the quinolones/fluoroquinolones, have the lowest rate of degradation and the highest resistance formation potential and provides a method which could be used to create a mechanistic model that can assess antimicrobial resistance formation potential. This study provides valuable evidence that high levels of antibiotic resistant E. coli are present in urban wastewater, and highlights the need for the development of international guidelines regarding regulation, monitoring and reporting of antibiotics and antibiotic resistant bacteria in the urban wastewater and receiving environments.
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