Molecular identification, typing and antimicrobial susceptibility screening of Vibrio anguillarum causing vibriosis in fish

Vibriosis is the most common bacterial fish disease in fish farms and causes severe losses. Vibrio anguillarum is the main effect of the disease. Vibrio ordalii is the closest biotype of the V.anguillarum. For this reason, it is necessary to use more than one molecular method to distinguish these two biotypes and to confirm the identification. The organisms used in this study were obtained from stocks of Ege University Aquaculture Department. These isolates are isolates that cause Vibriosis disease and only phenotypic diagnosis has been made. Molecular biological methods have been used to ensure their diagnosis at the genus and species level. First of all, 16S-rDNA sequence analyzes of isolates have been started. Sequences were performed using Generic and genus specific 16s-rDNA primers. As a result of the sequence all isolates were included in the vibrio genus. Vibrio anguillarum and Vibrio ordalii are genotypically similar over 97%. For this reason, the RFLP of the groEL gene region was constructed to distinguish these two species. The 1117 bp region of the groEL gene region was amplified by PCR using primers specific for the vibrio genus. It has been observed that the genomic region of the replicated groEL gene has fragmentation of Vibrio anguillarum as a result of cutting with species-specific restriction enzymes. For a more detailed distinction, the groEL gene region has been sequenced. In the obtained sequence results, all isolates were identified as 99% V. anguillarum. In addition, the diagnosis was confirmed using species specific primers specific to another region of groEL and the amiB gene region. All of the isolates gave positive results. In addition, in this study, Vibrio anguillarum strains identified above and the general antibiotics used in the treatment of fish diseases have been tested by antibiogram screening. As a result of the test, all of the strains were sensitive to the antibiotics used.