Background and Objective:
Antimicrobial resistance (AMR) is a major threat to modern medicine and expected to become one of the leading global health challenges of the century. Resistant infections in animals are known to be important drivers of AMR in humans, however, the extent of their contribution is not clear. To adequately assess the total economic and public health burden posed by animal diseases, as well as optimally inform effective AMR mitigation and control strategies, a better understanding of the relative impact of animal AMR on humans is crucial. Source attribution studies are valuable tools for the partitioning of health burdens to specific sources and thus well suited for this purpose. The aim of this systematic literature review is to summarize the available evidence from source attribution studies and other studies that quantify the direct contribution of animal sources of AMR to resistant infections in humans, focusing on bacterial AMR.

Methods:
Our initial search of four scientific databases (Pubmed, Web of Science, Scopus and Embase) yielded 16,955 results published between 1957 and 2022. Articles will be selected for eligibility based on whether they attribute bacterial AMR in humans to animal-related sources, which we defined as livestock, aquaculture, foods of animal origin and companion animals. We also intend to perform meta-analyses with the results of relevant studies of animal-related risk factors for sporadic resistant infections in humans to derive population attributable fractions.

Results and conclusion:
We will provide an overview of the currently available evidence on the impact of zoonotic AMR on human health, outline important knowledge gaps and discuss suitable methods for future research.