Resistance integrons. Mini review

Integrons represent genetic mechanisms that allow bacteria to adapt and evolve rapidly through the stockpiling. The genes are embedded in a specific genetic structure called gene cassette (a term that is lately changing to integron cassette) that typically carries one promoterless ORF together with a recombination site (attC). Additionally, an integron will usually contain one or more gene cassettes that have been incorporated into it. The gene cassettes may encode genes for antibiotic resistance. In recent years, they have had a crucial role in the acquisition, expression, and dissemination of antibiotic resistance genes. Therefore, the ongoing threats posed by integrons require an understanding of their origins and evolutionary history. This review examines the functions and activities of integrons. It shows how antibiotic use selected particular integrons from among the environmental pool, so that integrons carrying resistance genes are now present in the majority of Gram-negative pathogens. In closing, it examines the potential consequences of widespread pollution with the novel integrons in Iran and the world.