ESBL genes in Escherichia coli in One Health perspective, molecular evidence, and transmission routes

Antimicrobial resistance (AMR) caused by Extended Spectrum β-Lactamase (ESBL)-producing bacteria has emerged as a major global public health threat, involving complex interactions among humans, animals, and the environment. Among ESBL-producing pathogens, Escherichia coli is recognized as one of the most important bacteria due to its remarkable genetic adaptability, which facilitates the widespread dissemination of β-lactam resistance genes through horizontal gene transfer mechanisms. This review aims to examine the molecular evidence of ESBL genes in E. coli, the characteristics of high-risk clones, mobile genetic elements involved in dissemination, and transmission pathways from a One Health perspective. Evidence from numerous studies demonstrates the predominance of the bla_CTX-M gene family, particularly the CTX-M-15 variant, in E. coli isolates derived from humans, food-producing animals, companion animals, wildlife, and environmental sources. High-risk clones such as ST131 and ST1193 play a crucial role in the global spread of ESBLs because of their strong colonization capacity, persistence, virulence, and ability to accumulate multiple antimicrobial resistance determinants. Furthermore, the interplay between antimicrobial usage, ecosystem dynamics, and the mobility of genetic elements such as plasmids, transposons, and integrons accelerates the cross-sector dissemination of ESBL-producing E. coli. These findings highlight the urgent need for integrated control strategies based on the One Health framework, including molecular surveillance, rational antimicrobial stewardship, and strengthened environmental management, to sustainably mitigate the spread and impact of antimicrobial resistance worldwide.