Molecular characterization of antibiotic resistant Vibrio harveyi isolated from shrimp aquaculture environment in the south east coast of India.

Vibrio harveyi is a strategic human pathogen that occurs naturally in marine and estuarine environments. The pathogen is believed to cause acute septicemia, gastroenteritis, severe necrotizing soft-tissue infection, and high rate of lethality through ingestion of V. harveyi contaminated seafood. In this study, we isolated and characterized V. harveyi from water suspended sediment samples of black tiger shrimp ponds and from the sea coasts, in the east coast of the Bay of Bengal, India. Initial isolations of putative V. harveyi isolates were grown on thiosulfate-citrate-bill salts-sucrose agar (TCBS) plates for 36 h. Gram-negative and oxidase-positive colonies alone were selected and subsequently identified by 12 different conventional biochemical tests. The species specificity was confirmed by 16S rRNA, hemolysin and toxRvh genes were used through PCR targeted primers. Furthermore, genomic fingerprinting was carried out using randomly amplified polymorphic DNA fingerprinting, which showed that all the five V. harveyi were genetically distinct. From a total of 256 samples, a total of five strains of V. harveyi were isolated, of which three were from various shrimp ponds and two were from the coastal area. These five isolates were subjected to profiling against 15 antibiotics and the perusal results emphasized the V. harveyi resistance to ciprofloxacin, penicillin, rifampicin, and vancomycin compared to other tested antibiotics. The present findings were helpful in understanding the multiple antibiotics resistance of V. harveyi, which indicates the urgent need for targeted alternative biocontrol strategies to enhance the prospects of commercially viable shrimp cultivation.