2.3 Transmission between animal, human and environment

Transmission – the transfer of resistant bacteria or ARGs from one area or host to another – is one of the five research priorities identified by the Quadripartite.

Listed below is a non-exhaustive list of research areas and topics highlighted in the Quadripartite report.The purpose of highlighting these here is to increase awareness of the importance of combating AMR from a One Health perspective. This course will focus on quantifying the AMR burden in human health, but learners should be aware that the transmission of ARGs can happen between animals, humans and the environment, contributing to the AMR burden of each system (see Altevogt et al., 2025).

What is known so far about AMR transmission?

• Several studies have modelled the transmission of AMR in agri-food chains and in human healthcare facilities and clinical settings.
• Microorganisms (including bacteria) can exchange genes, with some restrictions, across interconnected, shared environments of human, animal, plants, water and soils microbiomes.
• Antibiotic resistance genes (ARGs) that are responsible for phenotypic resistance against clinically important antibiotics for disease treatment can cross environmental habitat boundaries and be transferred between non-clinical, environmental microorganisms and human pathogens.

What are the data and research gaps?

• Research on AMR in plant production is still limited.
• There is lack of understanding of transmission dynamics of AMR in low- and middle-income settings.
• The role of the environment as a reservoir of AMR and its impact on human health burden are not fully understood.
• Transmission risk across human, animals, plants, water and soil, and the drivers, still need further exploration.