The Adaptive Genetic Arsenal of Pathogenic Vibrio Species: the Role of Integrons

This chapter discusses the specific roles of integrons in the adaptive capacity of the Vibrionaceae, with emphasis on pathogenic Vibrio species and antibiotic resistance. Even though many reports have demonstrated that the presence of antibiotic resistance genes in plasmids or integrons in V. cholerae was the cause of resistance to antimicrobial agents, the mechanism of resistance in other cases was unknown. Integrons likely correspond to one of the most refined tools selected by bacteria, as suggested by the data collected during the last 15 years. The authors recommend using the single term integron to describe all types of integron structures, supporting this suggestion with the fact that the different integrons use the same recombination processes and machinery. The integron gene cassettes for which an activity has been experimentally demonstrated, be they from superintegrons (SI) arrays or from soil DNA, encode proteins related to simple enzymatic functions; their recruitment is seen as providing the bacterial host with an adaptive advantage. Both experimental and phylogenetic data suggest that SIs are the source of the mobile integrons (MI) and resistance gene cassettes observed within clinical isolates.