# Transmission and Evolution of Antibiotic Resistance Genes and Antibiotic-Resistant Bacteria in Animals, Food, Humans and the Environment

## TL;DR

This review explores how antibiotic resistance spreads across animals, food, humans, and the environment, highlighting the role of gene transfer and interconnected drivers.

## Contribution

The paper provides an integrated One Health framework to understand and mitigate the transmission of antibiotic resistance.

## Key findings

- Antibiotic-resistant bacteria and genes are widespread across all ecological compartments.
- Horizontal gene transfer via mobile elements like plasmids accelerates resistance spread.
- Multiple interconnected drivers promote cross-ecosystem transmission of resistance.

## Abstract

Antimicrobial resistance (AMR) constitutes one of the most severe and pressing threats to global public health, food security, and environmental integrity. This review synthesizes current evidence across interconnected One Health domains—humans, animals, food, and the environment—to delineate the scope, mechanisms, and drivers of AMR transmission. Our analysis reveals three principal findings. First, the scope of AMR is alarmingly extensive, with antibiotic-resistant bacteria (ARB) and genes (ARGs) now pervasive across all four ecological compartments, transcending traditional clinical boundaries. Second, this widespread distribution is critically facilitated by horizontal gene transfer mechanisms, particularly via mobile genetic elements such as plasmids, which enable ARGs to disseminate rapidly between diverse bacterial populations across different ecosystems. Third, we identify multiple interconnected drivers that actively promote this cross-ecosystem spread, encompassing both evolutionary and transmission drivers. By characterizing these critical transmission pathways and underlying drivers, this review provides an integrated framework to identify critical transmission risks and inform integrated strategies for mitigating antimicrobial resistance across One Health domains.