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Title: Investigating wastewater treatment plant impact on antibiotic resistance within UK river systems
Author: Hill, Gemma
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 2016
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Antimicrobial resistance (AMR) presents one of the most important threats to human health of the 21st century. The recent report on AMR predicted that by 2050 10 million deaths a year will be directly attributable to AMR bacterial infections. The dissemination of antibiotic resistance genes (ARG) in to the environment has previously been highlighted as an important route of transmission and was investigated in the current study. Wastewater treatment plants (WWTP) have been highlighted to contribute to ARG pollution of rivers focusing on effluent impact on receiving water bodies. In this study the aim was to further investigate the effects of WWTP effluent on the receiving river, but also investigate the release of raw sewage resulting from combined sewer overflow (CSO) events on the receiving river. This study found that sediment samples carried a higher abundance of all ARG and therefore present a greater risk compared to water and that CSO spills are important in the spread of ARG likely contributing more substantially to the environmental spread of resistance than continuous release of treated wastewater. In addition, the present study aimed to investigate the genetic potential of viable, potentially pathogenic Escherichia coli isolates from the river sediment to determine whether these human opportunistic pathogens carried the genetic capacity to spread resistance and cause disease. E. coli strains were shown to carry extensive resistance to many clinically relevant antibiotics, metals and biocides as well as carrying vast virulence-associated genes. This study identified ST940 as an important sequence type (ST) in the dissemination of the ESBL blaCTX-M-15 gene and suggests further work to investigate the importance of this ST type in the transmission of this clinically important ARG. The work presented here supports previous studies demonstrating extensive environmental ARG dissemination in rivers as a direct result of WWTP impacts and further highlights rivers as an important reservoir of ARG and antibiotic resistant bacteria (ARB). The discovery of clinically important viable E. coli isolates in sediment suggests more rigorous methods of wastewater treatment, specifically a reduction in the number of CSO release events, must be employed if further dissemination of ARB is to be prevented.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QR Microbiology