Non pathogenic Vibrio environmental strains as a marine reservoir of virulence, fitness and antibiotic resistance genes and mobile genetic elements

Introduction Pathogenic Vibrio species are of major concern as they are responsible for infectious diseases in humans. However, other Vibrio species found in the aquatic environment and defined as non pathogenic for humans, such as Vibrio alginolyticus, Vibrio harveyi, Vibrio anguillarum, Vibrio fluvialis and others are also of interest in that, although rarely, they have been isolated in association with infections in humans. Although it has been largely considered that environmental bacterial isolates lack those virulence genes which usually are found in clinical strains, few recent studies indicate that virulence genes, or their homologous, could also be present in strains from environmental sources and that acquisition of such genes might have place in the aquatic environment. In this study we have screened a collection of marine Vibrio strains isolated in the area of the Venetian Lagoon for the presence of virulence and fitness genes usually present in V. cholerae and V. parahaemolyticus pathogenic strains. The collection has been also screened for the presence of antibiotic (AR) resistance traits. Particular interest has been dedicated to the detection and analysis of mobile genetic elements such as the V. cholerae pathogenicity island VPI-2 and the class 1 integron.