One Health drivers of antibacterial resistance: quantifying the relative impacts of human, animal and environmental use and transmission

Objectives: Antibacterial resistance (ABR) is a major global health security threat, with a disproportionate burden
on lower-and middle-income countries (LMICs). It is not understood how ‘One Health’, where human health is
co-dependent on animal health and the environment, might impact the burden of ABR in LMICs. Thailand’s 2017
“National Strategic Plan on Antimicrobial Resistance” (NSP-AMR) aims to reduce AMR morbidity by 50%
through 20% reductions in human and 30% in animal antibacterial use (ABU). There is a need to understand the
implications of such a plan within a One Health perspective.
Methods: A model of ABU, gut colonisation with extended-spectrum beta-lactamase (ESBL)-producing bacteria
and transmission was calibrated using estimates of the prevalence of ESBL-producing bacteria in Thailand. This
model was used to project the reduction in human ABR over 20 years (2020–2040) for each One Health driver,
including individual transmission rates between humans, animals and the environment, and to estimate the longterm
impact of the NSP-AMR intervention.
Results: The model predicts that human ABU was the most important factor in reducing the colonisation of
humans with resistant bacteria (maximum 65.7–99.7% reduction). The NSP-AMR is projected to reduce human
colonisation by 6.0–18.8%, with more ambitious targets (30% reductions in human ABU) increasing this to
8.5–24.9%.
Conclusions: Our model provides a simple framework to explain the mechanisms underpinning ABR, suggesting
that future interventions targeting the simultaneous reduction of transmission and ABU would help to control
ABR more effectively in Thailand.