Isolation, Identification and Molecular Characterization of Vibrio parahaemolyticus from Shrimp Samples from South Gujarat of Navsari District

Shrimp cultivation faced serious problems with diseases caused by viruses and bacteria causing severe economic losses. Of the bacterial infections, Vibrio parahaemolyticus, have been frequently associated with fatalities both, in hatcheries and grow out ponds. V. parahaemolyticus is pathogenic to human besides fish and other aquatic lives. For systematic bacteriological examination of aseptically collected all samples were brought to the laboratory in Ice box and they were further processed for isolation, identification and characterization of V. parahaemolyticus isolates on the basis of their morphological, cultural and biochemical characteristics. Out of total 150 samples of shrimp 5 (3.33%) isolates of V. parahaemolyticus were obtained which included 3 (4.28%, 3/70) from marine shrimp samples and 2 (2.5%, 2/80) from freshwater shrimp samples. Out of 27 samples of the hand swabs of fish handlers, 2 (7.40%) were positive for V. parahaemolyticus. However, none of 23 human stool samples was positive for the pathogen. The pathogenicity of 7 isolates of V. parahaemolyticus was tested on Wagatsuma agar contained human red blood cells. Only one V. parahaemolyticus isolate (33.33%, 1/3) cultured from marine shrimp sample was Kanagawa Phenomenon positive, expressing β-haemolysin on Wagatsuma agar. Rest of all the isolates were KP negative. all 7 V. parahaemolyticus isolates amplified the species specific toxR (368 bp) gene. While ruling out pathogenic nature of the isolates by PCR, 1 out of 7 (14.28%) isolates exhibited amplification of virulent tdh (269 bp) gene. However, not a single V. parahaemolyticus isolate contained trh (500bp) gene.