One Health Perspective of Antimicrobial Resistance: Interconnections between Humans, Animals, Food and the Environment

Abstract

Antimicrobial resistance (AMR) is one of the most pressing global public-health threats, associated with approximately 5 million deaths in 2019 and projected to cause up to 8.22 million deaths annually by 2050 if unaddressed, with the burden falling disproportionately on low- and middle-income countries. This chapter argues that AMR cannot be understood or controlled as a clinical problem alone, but must be addressed as a One Health challenge in which resistant organisms and resistance genes circulate continuously among four interconnected domains: human health, animal health, food production, and the environment. We review the molecular mechanisms underlying resistance emergence and spread, including horizontal gene transfer, mobile genetic elements, biofilm-mediated persistence, and co-selection by heavy metals and other environmental contaminants, and examine how antimicrobial use in human medicine, livestock, and aquaculture, together with inadequately managed waste and wastewater, sustains selective pressure across sectors. Particular attention is given to priority pathogens of cross-sectoral concern (including ESKAPE (E) organisms, carbapenem-resistant Enterobacterales, MRSA, VRE, and colistin- and fluoroquinolone-resistant zoonotic bacteria), the farm-to-fork transmission of resistant bacteria and antimicrobial residues through food systems, and the role of wildlife, climate change, and human mobility in disseminating resistance across geographic and ecological boundaries. The chapter further evaluates current surveillance frameworks (including WHO's GLASS system), antimicrobial stewardship across human and veterinary medicine, emerging technologies such as genomic and metagenomic surveillance, artificial intelligence, and CRISPR-based diagnostics and therapeutics, and the global governance architecture led by the FAO–WHO–WOAH–UNEP Quadripartite. Persistent gaps remain in cross-sectoral data integration, environmental surveillance, equitable access to diagnostics and treatment, and internationally enforceable regulation, particularly in resource-limited settings. We conclude that meaningful progress against AMR will require treating human, animal, food, and environmental health not as separate policy domains but as a single interconnected system demanding coordinated, adequately resourced, and equitable One Health solutions.