Integrons in the Age of Antibiotic Resistance: Evolution, Mechanisms, and Environmental Implications: A Review

Integrons, which are genetic components commonly found in bacteria, possess the remarkable capacity to capture gene cassettes, incorporate them into their structure, and thereby contribute to an increase in genomic complexity and phenotypic diversity. This adaptive mechanism allows integrons to play a significant role in acquiring, expressing, and spreading antibiotic resistance genes in the modern age. To assess the current challenges posed by integrons, it is necessary to have a thorough understanding of their characteristics. This review aims to elucidate the structure and evolutionary history of integrons, highlighting how the use of antibiotics has led to the preferential selection of integrons in various environments. Additionally, it explores their current involvement in antibiotic resistance and their dissemination across diverse settings, while considering potential transmission factors and routes. This review delves into the arrangement of gene cassettes within integrons, their ability to rearrange, the mechanisms governing their expression, and the process of excision. Furthermore, this study examines the presence of clinically relevant integrons in a wide range of environmental sources, shedding light on how anthropogenic influences contribute to their propagation into the environment.