Summary. The rapid spread of antibiotic resistance has significantly limited treatment options, increased mortality rates of infections and has become a major clinical and public health problem. Integrons are genetic platforms carried by plasmids or contained within a transposon, and their role in the dissemination of resistance genes among bacteria has been well established and documented. Mobile integrons of class 1 are the most ubiquitous and have been the most commonly reported among clinical bacteria and are predominantly associated with Gram-negative bacterial pathogens. Although there is a number of currently available studies of class 1 integrons, only a limited number of processes crucial to the understanding of integron biology have been elucidated. Among these processes are the molecular mechanism of integrase gene expression as well as gene cassette expression in different bacterial pathogens.