Variability in the regulation of medically important antimicrobials among countries: A One Health approach.

The One Health approach recognizes that antimicrobial monitoring and regulations must jointly address the risks of antimicrobial resistance in human and animal health for effective strategy and policy to achieve global public health. We operationalize this principle by integrating the World Health Organization's human importance classifications with the World Organization for Animal Health's veterinary classifications to create a hierarchical framework that prioritizes human health. This framework underpins our unique "One Health Score" (OHS), to evaluate regulatory compliance of country-specific drug residue limits with international standards of Codex. Codex, the European Union, and the United States are identified as leaders of establishing maximum residue limits to which other countries defer to. Among pairs with medical classifications, 53% fall under the pairing of Highly Important Antimicrobials (H3) for humans and Veterinary Critically Important Antimicrobials (V1) for animals. The One Health Score is non-negative for at least 50% of countries at each medical importance level. However, 21% of the countries with H3V1 MRLs are laxer than Codex. Drugs with a high market demand in animal agriculture are the most commonly regulated among countries. This suggests drugs used less in food animals may not be adequately regulated currently, despite, in some cases, being highly important for human health. Country officials must balance economic and health priorities when setting or modifying drug residue limits.