Asian-Pacific Aquaculture 2019

June 19 - 21, 2019

Chennai Tamil Nadu - India

OCCURRENCE OF HUMAN AND SHRIMP PATHOGENIC Vibrio SPECIES. IN WILD-CAPTURED AND FARMED FISH AND SHELLFISH

Vandita Kohli*, Manjusha Lekshmi, Sanath Kumar, Binaya Bhusan Nayak and K.V. Rajendran
*Fisheries Resources, Harvest and Post-Harvest Division, Central Institute of Fisheries Education, Versova, Mumbai.
vanditakohli5@gmail.com
 

Among over 100 species of the genus Vibrio, a few such as V. cholerae, V. parahaemolyticus and V. vulnificus are known human pathogens. Several other potentially pathogenic Vibrio spp. are not well understood with regards to their virulence characteristics. Similarly, V. harveyi and V. parahaemolyticus are important pathogens of farmed shrimp. In the present study, the occurrence and virulence properties of some of the common Vibrio spp. were tested in fresh fish and shellfish.  A total of 50 seafood and environment samples comprising of 11 finfish, 13 shrimp, 12 water and 12 sediment samples were collected from landing centres, retail markets and shrimp farms in and around Mumbai. Altogether, 432 strains of Vibrio were isolated after selective isolation and biochemical characterisation. The isolates were subjected to further identification by PCR using species-specific primers for V. cholerae, V. parahaemolyticus, V. harveyi, V. mimicus and V. alginolyticus. V. cholerae and V. parahaemolyticus were identified by toxR and tlh specific PCR, respectively while V. harveyi, V. mimicus and V. alginolyticus were distinguished by 16SrRNA-specific PCR. All the isolates were screened for the presence of Vibrio-specific virulence genes ctxAB, tdh and trh by PCR. Overall, 380 isolates were confirmed to be Vibrio spp., of which 216 were V. parahaemolyticus harbouring one or more virulence genes. The remaining were V. harveyi (94), V. alginolyticus (38), and V. mimicus (4). V. cholerae was not isolated from any of the samples. A few isolates of V. harveyi showed the presence tl (thermolabile hemolysin) of V. parahaemolyticus. Sequences of toxin genes such as tdh and ctxAB were found in some non-V. cholerae, non-V. parahaemolyticus isolates suggesting wider distribution of virulence gene sequences among Vibrio spp. None of the V. parahaemolyticus isolates belonged to the Acute Hepatopancreatic Necrosis Disease (AHPND)-causing clonal group.