Occurrence, characterization and antimicrobial susceptibility of Vibrio alginolyticus in the Eastern Adriatic Sea

•Occurrence of Vibrio in marine water and fish samples was examined.•DNA sequencing confirmed identified isolates as Vibrio alginolyticus.•Differences between obtained isolates were not determined.•Antimicrobial susceptibility of isolated V. alginolyticus was analysed.•Isolates were susceptible to flumequine, chloramphenicol and oxytetracycline.

In 2007-2008, 162 samples (72 marine water samples, 90 swabs from the gills and skin) were collected from three European seabass fish farms in Eastern Adriatic. The aim of study was to determine the occurrence of Vibrio, to identify the isolated strains and to investigate their antimicrobial resistance. The comparison of the results obtained in spring and autumn periods indicated a higher Vibrio concentration in spring samplings. The greatest prevalence of Vibrio alginolyticus was on gills than on skin, whereas statistically significant differences were obtained between sampling periods with maximal prevalence in spring. Vibrio isolates from the marine water and from swabs of European seabass were analysed by DNA sequencing of partial 16S rDNA and gyrB genes and identified as V. alginolyticus. Isolates were highly susceptible to flumequine, chloramphenicol and oxytetracycline.