Environmental reservoirs of antibiotic resistance genes and their transmission to humans

The emergence and dissemination of antibiotic resistance genes (ARGs) represent one of the most pressing global health challenges of the 21st century. While clinical settings have traditionally been considered the primary source of antibiotic resistance, mounting evidence suggests that environmental reservoirs play a critical role in the maintenance, evolution, and transmission of ARGs to human populations. This review examines the diverse environmental compartments that serve as reservoirs for ARGs, including soil, water bodies, wastewater treatment plants, agricultural settings, and the wildlife microbiome. We explore the mechanisms of horizontal gene transfer that facilitate ARG dissemination across environmental and clinical contexts, and discuss the pathways through which environmental ARGs reach human populations. Understanding the environmental dimensions of antibiotic resistance is essential for developing comprehensive One Health strategies to mitigate this growing threat to public health, food security, and economic stability.