Investigating selection and co-selection for antimicrobial resistance by non-antibiotic drugs and plant protection products

Lead Research Organisation: University of Exeter
Department Name: University of Exeter Medical School

Abstract

A growing body of research has demonstrated low concentrations of antibiotics can select for antimicrobial resistance. The first paper showing non-antibiotic drugs (NADs) can select for antimicrobial resistance (AMR) in human gut-associated strains has just been published, raising concerns for selection for AMR in vivo. NADs are also present in waste water treatment plants, alongside antibiotics and other antimicrobial compounds where they are present as micropollutants. This cocktail of potentially selective contaminants will be present in sewage sludge, which is applied to agricultural soils as a fertiliser alongside plant protection products (PPP). How these multiple pressures may interact to select for AMR in terrestrial environments and how they impact microbial diversity is a completely novel research area, with the potential to influence policy at an international level, inform sustainable agricultural practices, and improve fundamental understanding of AMR evolution and microbial ecology.

Publications

10 25 50
 
Description Evidence has shown that when bacteria are exposed to non-antibiotic agents (e.g. metals), they become stressed and can develop resistance to that agent in order to survive. The resistance they develop may also be affective against antibiotics (co-selection). Plant protection products (PPPs) include herbicides, fungicides, insecticides and antibiotics. They are applied repeatedly at high concentrations and quantities, directly to the environment. Little is known about the affects of PPPs on the bacterial communities to which they are applied, particularly with regards to antibiotic resistance and co-selection. Initial experiments have demonstrated that exposure to some non-antibiotic PPPs significantly decreases the growth of a microbial community, at concentrations below their application concentration. A decrease in community growth has previously been shown to be a good proxy for selection for resistance genes. Future experiments will explore this further.

Further experiments have looked at the use of antibiotics as plant protection products. Literature searches produced evidence that ~10 different antibiotics are used in crop protection. 4 of these are of the aminoglycoside class. Streptomycin, Gentamycin, Kasugamycin and Validamycin. Streptomycin and Kasugamycin are two of the most commonly used antibiotics on crops. Kasugamycin is a crop specific antibiotic. We investigated if kasugamycin could select for resistance to other clinically relevant antibiotic resistance genes. We also explored the range of concentrations that streptomycin and gentamycin may select for resistance at. At present there is little evidence of kasugamycin's selective abilities. However, further investigation is required.
Exploitation Route The information from these experiments could provide the selective concentration ranges of antibiotic PPPs. This may inform policy makers who allow the use of antibiotics in crops in some countries and intermittently allow the use of it in countries such as America. It may also provide evidence of co-selection by non-antibiotic plant protection products, something which has not been thoroughly researched and may also impact policy in the future.
Sectors Agriculture, Food and Drink,Chemicals,Healthcare

 
Description Selection for antimicrobial resistance by plant protection products - analysis of established experimental field sites
Amount £9,183 (GBP)
Funding ID NE/T014326/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 04/2020 
End 09/2021
 
Description Poster presentation at the University of Exeter Microbiology Symposium 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Postgraduate students
Results and Impact Poster presentation giving an introduction to my research. The poster sparked in depth discussions and questions. In particular I had an in depth discussion with a student from another campus who wished to use some similar methods to what I planned.
Year(s) Of Engagement Activity 2019
 
Description Presentation at the College of Medicine and Health Annual Research Event 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Postgraduate students
Results and Impact Presentation to students of the college of medicine and health. Students are from the university but from two separate campuses in two different counties of the UK. Questions and discussions were sparked afterwards. The presentation updated students on my research which is on a very different topic to theirs. It allowed some networking across campuses.
Year(s) Of Engagement Activity 2020,2022
 
Description Presentation at the European Centre for Environment and Human Health 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Postgraduate students
Results and Impact Post graduate students attended the talks, it sparked questions and discussion after. The talk allowed me the share my research with students both working in similar areas and those who aren't. Further discussions were had with peers who work on similar topics about my research.
Year(s) Of Engagement Activity 2020,2021,2022
 
Description poster presentation at SETAC 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Presentation on my work to audiences at SETAC. Interesting conversation was had and questions were sparked, I was able to network with people working in the environmental AMR field but also with people who work with other chemicals and consider the environment and human health from that aspect.
Year(s) Of Engagement Activity 2020,2021,2022