Molecular characterizations of Vibrio parahaemolyticus in seafood from the Black Sea, Turkey

Vibrio parahaemolyticus is a marine bacterium that is considered as one of the major causes of bacterial food-borne outbreaks at a global scale. A total of 114 samples including mussel (n = 42), seawater (n = 22) and fish (n = 50) samples were collected and subjected to investigation. Vibrio parahaemolyticus was detected in 45 (39%) of 114 samples with an occurrence in mussel, seawater and fish samples of 76, 40·9 and 8% respectively. A total of 96 isolates were positive for the species-specific genes toxR and tlh and confirmed as V. parahaemolyticus. Presence of the virulence marker gene tdh was not identified in any of the strains investigated; however, four of strains were positive for the trh gene. Serological analysis of eight randomly selected trh-negative isolates identified three different serotypes: O4:K untypeable (KUT), O2:KUT, O3:KUT. Conversely, all four trh-positive strains belonged to a single serotype (O1:K1) and share an undistinguishable genetic profile by PFGE analysis, suggesting the existence of a dominant clone for the trh-positive strains in the region. Significance and Impact of the Study: Vibrio parahaemolyticus is the most prevalent food-poisoning bacterium associated with seafood consumption. The number of infections is increasing worldwide and is being reported in areas with no previous incidence. This study provides the first instance of the occurrence of V. parahaemolyticus strains with virulence traits in the Black Sea, contributing to gain a better understanding about potential risk associated with this pathogen in the region.