Farming practices a potential large driver of antimicrobial resistance

By Dr Felicity Elder, Post Doctoral Research Associate

Spreading manure from animals treated with antibiotics could be a large driver of anti-microbial resistance (AMR).  

As a post-doctoral researcher on the ‘Molecules to Landscape - Sanitation Led Agricultural Circular Economy’ project, I am working to better understand and quantify this driver. 

My specific work focuses on the fate of antibiotics and antibiotic resistance genes within manure, sludge and the soil to which they are applied.  

As waterways are the main receiver of human waste, there has been a large focus on wastewater entering the aquatic environment and the spread of anti-microbial resistance in the Global North.

This has led to the development of predicted no effect concentrations for AMR within the aquatic environment.   

However, this sort of information is lacking for the soil environment, where veterinary drugs enter the system when animal waste is spread on agricultural land as fertiliser.  

Farming within the UK and worldwide is facing another major threat – climate change. Increasing water scarcity and the need to reduce the carbon emissions of food are creating major implications on how we farm and the crops we can produce.   

With the increase in chemical fertiliser costs and the target for UK agriculture to meet NetZero by 2040 there is a real drive for the use of organic amendments as fertilisers.  

We therefore need an agricultural circular economy, where essential farming resources such as water, biomass and nutrients can be recycled through the reuse of sanitation waste solids, wastewater, and livestock manures. There is, however, very little known about the impact this may have on the spread and development of AMR.   

This led me to develop an assessment framework using current knowledge that can assess the AMR risk of applying slurry and manure to land, considering soil type and application method. This framework also highlights where further research is needed within this area if we are to curtail the spread of AMR. 

One Health: an interdisciplinary approach 

The One Health approach recognizes the linkages and interdependence between health of ecosystems, humans and animals.

AMR is considered a One Health issue, meaning that to tackle this global health problem we need to address the links between human, animal and environmental health.

There is a major knowledge gap on the implications this sort of change in farming practices will have on the spread of AMR within the environment.   

There are also major research and regulatory gaps as we have spent decades solely focusing on the aquatic environment.   

The Molecules to Landscape Project  

The Molecules to Landscape project is an interdisciplinary Biotechnology and Biological Science Research Council (BBSRC) and Natural Environment Research Council (NERC) funded project.

It aims to answer a couple of these questions through building across sector network and using laboratory human and pig gut models alongside agricultural systems to track two antibiotics and a resistance gene of national interest through sanitation led-agricultural circular economy.  

The aim is to answer the question as to whether there is a circularity, not only in the waste reuse, but also in the antibiotics and antibiotic resistance genes within the waste. This knowledge will help us support the safe transition to a sanitation led agricultural circular economy as we tackle the combined challenges of AMR, climate change and food security.  

Next Steps  

I originally trained as a medical microbiologist and spent several years working within the NHS as part of the regional antimicrobial reference laboratory.

Working across microbiology and analytical chemistry, monitoring antibiotic resistance within the region and concentrations of antibiotics in patients’ blood to ensure therapeutic success.

Through this work, I became increasingly interested in the fate of antibiotics and antibiotic resistant bacteria that are excreted in our urine and faeces, and their potential role in the spread of antibiotic resistance (AMR). Leading me to pursue a PhD looking at urban wastewater treatment plants as potential hotspots for antibiotic resistance. 

As I continue to develop as an independent researcher, I aim for my research is to help tackle AMR but also support the agricultural economy and food security.  

To ensure the applicability of my research, my findings have been and will be shared with farmers, regulators, policy makers, scientists, and other key stakeholders.   

And will hopefully bring together different sectors and disciplines to develop future collaborations as we tackle this complex challenge.