Antimicrobial resistance gene persistence in waste water treatment systems, the natural environment and patient samples in the Lothians

Antimicrobial resistance poses a major threat to health services on a global scale. Whilst bacteria harbouring antimicrobial resistant (AMR) genes are known to have existed in the environment preceding the medical use of antibiotics, their intensive use has resulted in a rapid increase in AMR gene diversity and prevalence. Currently, there is a lack of knowledge surrounding how different environmental factors influence the prevalence and dispersal of AMR genes. It is important to gain greater understanding these factors as it will enable the development of strategies to intercept and prevent sources of AMR spread.
The extensive therapeutic use of antibiotics has resulted in an increase in the level of antimicrobial resistant bacteria found in human faeces, making waste water treatment plants (WWTPs) a "hotspot" of resistant bacteria. The release of effluent into the surrounding environment and the use of biosolids as a fertiliser on agricultural land act as a significant point of entry for resistant bacteria and their AMR genes into the environment. The current project aims to improve our understanding of the contributing factors to the prevalence and persistence of AMR genes in WWTPs and in the environment. A list of primers targeting known resistance genes has been compiled, which the study will test and use in polymerase chain reaction (PCR) to investigate the abundance of a variety of AMR genes in a range of samples. Alongside the WWTP, soil and water samples will be taken from a diverse set of environments including agricultural land and rural/ urban areas, in order to assess the impact of human activity on AMR prevalence. The study will also utilize lab-scale bioreactors and microcosms, reflecting real-world WWTPs and environments to investigate factors influencing the persistence of a select number of clinically relevant AMR genes over time and their prevalence amongst microbial communities under differing conditions. This may include operating conditions used in WWTPs.
Another area the project will explore aims to increase our understanding regarding the role of the environment in the transmission of clinically relevant AMR genes to the human population. This will be addressed by performing PCR on faecal samples collected from healthy human volunteers in Edinburgh. The abundance of AMR genes will be compared to those observed in the environmental samples, in order to establish whether there is any correlation. This will help build a clearer picture detailing the extent to which AMR genes in the environment impact the human population.