The Effects of Restricting Antimicrobial Use in Food-Producing Animals on Antimicrobial Resistance in Humans: a Review

Abstract

Resistance to antimicrobials is an important and growing concern for human health worldwide, as it reduces the efficacy of antimicrobial treatments, leading to longer illness and increased mortality. Antimicrobial use in food producing animals can increase the prevalence of antimicrobial resistant bacteria in animals. Subse quently, this resistance can be transmitted to humans through the foodborne pathway. Reducing antimicrobial use in food producing animals could therefore limit resistance in humans. In light of possible negative effects of reducing antimicrobial use, it is important that the effects of a restriction in antimicrobial usage can be predicted, so a cost benefit analysis can be made to inform policy makers. This review provides an overview of the available research on the effects of restricting antimicrobial use in food producing animals on antimicrobial resistance in humans. A literature search resulted in 14 papers being included, that constructed either a model or analysing a change in policy. All included papers showed a decrease in resistance in humans foll owing a restriction in antimicrobial use, with the exception of one paper where no significant difference was observed for one of the antimicrobials investigated. The effect sizes varied to a large extent between studies, which can be partly ascribed to th e different bacteria and antimicrobials investigated. However, a lack of information on the change in antimicrobial use is a major shortcoming of almost all studies. More research is needed to reliably estimate the impact of restricting antimicrobial use i n food animals on resistance in humans. This future research should also focus on quantifying the change in antimicrobial usage following a restriction.