• Journal of Fisheries and Marine Sciences Education
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• v.26 no.6
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• pp.1193-1200
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• 2014

Edwardsiella tarda, Streptococcus iniae and S. parauberis are main bacterial pathogens in aquaculture farms of olive flounder, Paralichthys olivaceus. We have discussed the efficacy and safety of 3 type-combined vaccines (A: S. iniae 1mg + S. parauberis 1mg + E. tarda 1mg, B: S. iniae 1mg + S. parauberis 1mg + E. tarda 0.5mg, C: S. iniae 1.5mg + S. parauberis 1.5mg + E. tarda 1mg) through intraperitoneal injections in olive flounder. None of the vaccines gave rise to any signigicant side effects on histopathology and blood chemistry. The antibody titers and lysozyme activities of A type were higher than those of B, C and control. Four weeks after vaccination, RPS (relative percent survival rates) was 62.5~75% (A type), 50~66.7% (B type) and 55.6~62.5% (C type) respectively. As the results, the combined vaccines are possible to prevent edwardsiellosis and streptococcosis, and A type : S. iniae 1mg + S. parauberis 1mg + E. tarda 1mg, is the most effective out of them.

• Journal of Marine Bioscience and Biotechnology
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• v.1 no.3
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• pp.218-223
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• 2006

The present study evaluated effect of egg yolk immunoglobulin (IgY) from the hen immunized with Edwardsiella tarda. The purification of anti-E. tarda IgY was performed by polyethylene glycol (PEG). Purified IgY had heavy chain of 64 kDa and light chain of 27 kDa size. The IgY was instable against olive flounders digestive factors and artificially modulated pH 2 and 3. Nevertheless, some activity of IgY appeared in intestine. IgY was orally administered with viable E. tarda to the olive flounders and the efficacy of protection against E. tarda infection was evaluated. Orally administered IgY at a dose of 20 mg/fish delayed infection period of E. tarda cannulated at $10^{6{\sim}8}CFU/fish$ to small size (30~40 g) and middle size (110~120 g) flounder. Moreover, orally administered IgY at dose of 20 mg/fish inhibited the penetration of E. tarda cannulated at $10^8CFU/fish$ into the liver, kidney, spleen and gill via intestine. The fish orally administered with IgY showed increased survival rate. These results suggest that egg yolk containing anti-E. tarda IgY is effective in preventing edwardsiellosis.

• Journal of Microbiology and Biotechnology
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• v.33 no.5
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• pp.668-679
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• 2023

Edwardsiella tarda is one of the most significant fish pathogens, causes edwardsiellosis in a variety of freshwater fish species, and its antibiotic resistance against multiple drugs has made it a health risk worldwide. In this study, we aimed to investigate the antibiotic resistance (ABR) genes of E. tarda and establish its antibiotic susceptibility. Thus, 540 fish (299 Oreochromis niloticus, 138 O. mossambicus, and 103 O. aureus) were collected randomly from twelve fish farms in three districts of Punjab in Pakistan. E. tarda was recovered from 147 fish showing symptoms of exophthalmia, hemorrhages, skin depigmentation, ascites, and bacteria-filled nodules in enlarged liver and kidney. Antimicrobial susceptibility testing proved chloramphenicol, ciprofloxacin, and streptomycin effective, but amoxicillin, erythromycin, and flumequine ineffective in controlling edwardsiellosis. Maximum occurrence of qnrA, blaTEM, and sul3 genes of E. tarda was detected in 45% in the liver, 58%, and 42% respectively in the intestine; 46.5%, 67.2%, and 55.9% respectively in O. niloticus; 24%, 36%, and 23% respectively in summer with respect to fish organs, species, and season, respectively. Motility, H₂S, indole, methyl red, and glucose tests gave positive results. Overall, E. tarda infected 27.2% of fish, which ultimately caused 7.69% mortality. The Chi-squared test of independence showed a significant difference in the occurrence of ABR genes of E. tarda with respect to sampling sites. In conclusion, the misuse of antibacterial agents has led to the emergence of ABR genes in E. tarda, which in association with high temperatures cause multiple abnormalities in infected fish and ultimately resulting in massive mortality.

• Journal of fish pathology
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• v.22 no.3
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• pp.327-334
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• 2009

This study was performed to verify the efficacy and safety of vaccine mixed formalin killed Edwardsiella tarda and formalin killed Streptococcus iniae in olive flounder Paralichthys olivaceus. Sera were obtained from each group at 2, 4, 6 and 8 weeks after vaccination and agglutination titers to E. tarda and S. iniae were determined using the microtiter method. Three weeks after vaccination, the fish challenged by intraperitoneal injection of E. tarda or S. iniae and immunization resulted in a relative percentage survival (RPS) of above 81.0-92.8%. Neither the groups vaccinated nor control groups resulted in significantly reduced weight gain 140 days post-vaccination, but differences between the groups vaccinated and control groups were found at the early days post-vaccination. This results suggest that it is possible to prevent edwardsiellosis and streptococosis after a vaccination without affecting growth of olive flounder.

• Journal of fish pathology
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• v.25 no.3
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• pp.181-188
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• 2012

The minimum inhibitory concentration (MIC) of eight antibiotics against Edwardsiella tarda 49 strains isolated from olive flounder (Paralichthys olivaceus) was determined by the broth microdilution method. E. tarda showed 38.8% and 61.2% resistance to ampicillin and amoxicillin. Both resistance rates of E. tarda were 4.1% against ciprofloxacin and norfloxacin. The $MIC_{50}$ values of oxytetracycline, amoxicillin and oxolinic acid were $64{\mu}g/ml$, $32{\mu}g/ml$ and $4{\mu}g/ml$. The $MIC_{50}$ value to ciprofloxacin was $0.25{\mu}g/ml$ which was lowest among eight antibiotics tested.

• Journal of fish pathology
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• v.28 no.1
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• pp.17-26
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• 2015

The purpose of this study is to explore the possibility of essential oils and flavonoids improving the performance of antibiotics, proving a higher efficacy in the presence of natural substances against Edwardsiella tarda and Streptococcus iniae. Increased efficacy was observed in several cases: both essential oils and flavonoids increased antibacterial efficacy of oxytetracycline and flumequine against E. tarda by 2-fold; essential oils and flavonoids increased antibacterial efficacy of nalidixic acid against E. tarda by 4-fold; flavonoids increased antibacterial efficacy of josamycin against S. iniae by 4-fold. The results obtained in this study suggest that essential oils and flavonoids might be especially useful in increasing the antimicrobial activity of nalidixic acid and josamycin against E. tarda and S. iniae in fish. Natural compounds examined in this study could also be useful to help decrease the overuse of antibiotics in fish.

• Journal of fish pathology
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• v.10 no.1
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• pp.45-52
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• 1997

A protein-bound polysaccharide preparation, PS-K, isolated from Coriolus versicolor was evaluated for its ability to enhance resistance against Edwardsiella tarda, causal agent of classical edwardsiellosis in tilapia, Oreochromis niloticus. Fish treated with a dose rate of 0.1 mg PS-K $g^{-1}$ body weight were challenged by intraperitoneal injection of E. tarda with different concentrations. Against low burdens of injections($1.2{\times}10^7$ and $1.2{\times}10^8$ cfu/fish), PS-K treated fish did not show any mortality compared to 50% and 100% mortality of control groups, respectively. However there was no increase of resistance against challenge with high concentrations of E. tarda ($1.2{\times}10^9$ and $1.2{\times}10^{10}$cfu /fish) except few days delaying of death. Tilapia injected with PS-K one day after intraperitoneal inoculation of E tarda($1.2{\times}10^7$ cfu/fish) showed 100% survival rate compared to control group of 50% survival rate. The result indicates the potential of PS-K as a prophylactic agent in aquaculture. The increased antibody response in fish received PS-K one week prior to FKC administration suggested the influence of PS-K on the specific humoral immunity and increased resistance against bacterial infection.

• Journal of fish pathology
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• v.5 no.1
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• pp.29-35
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• 1992

This study was carried out in order to identify the biochemical and serological characteristics of Edwardsiella tarda isolated from cultured flounder, Paralichthys olivaceus in the east and south coast of Korea. During the year of 1990 and 1991, the number of isolated E. tarda were 131 strains. To identify the biochemical characteristics of them kinds of tests were conducted. The results represented that all the strains had the same biochemical characteristics, and their biochemical characteristics were no differences among strains. A serological analysis was carried out based on agglutination test with antiserum belonging to E. tarda serotype a (E-22), b (SU-138), c (SU-100) classfied in japan. The selected 10 isolates showed agglutinin titer of 5120-2560, 40-80 and below 40 against E. tarda serotype a, b and c, respectively. Sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE) profiles of cell proteins of selected 10 isolates were showed no differences in kinds and volumes of proteins among strains.

• Fisheries and Aquatic Sciences
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• v.16 no.4
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• pp.273-277
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• 2013

Vibriosis caused by Vibrio anguillarum and edwardsiellosis caused by Edwardsiella tarda are septicemic diseases of many commercially important freshwater and marine fishes, and threaten the aquaculture industry in Korea. Early diagnosis and accurate identification of these two bacterial species could help to prevent these diseases and minimize the damage to cultured marine species. This study designed a duplex polymerase chain reaction (PCR) method for the simultaneous detection of two major fish pathogens: V. anguillarum and E. tarda. Each pair of oligonucleotide primers exclusively amplified the target groEL gene of the specific microorganism. Twenty-two Vibrio and ten non-Vibrio enteric species were used to check the specificity of the primers, which were found to be highly specific for the target species, even among closely related species. The detection limit was 400 pg for V. anguillarum and 4 ng for E. tarda when mixed purified DNA was used as the template. This assay showed high specificity and sensitivity in the simultaneous detection of V. anguillarum and E. tarda from artificially inoculated seawater and fish.

• Journal of fish pathology
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• v.27 no.1
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• pp.35-45
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• 2014

In this study, we investigated the effects of dietary 1% garlic extract on nonspecific immune responses and fish diseases (Viral Hemorrhagic Septicemia Virus, Vibrio anguillarum, Streptococcus iniae and Edwardsiella tarda) resistance in olive flounder Paralichthys olivaceus. Fish were fed a commercial diets supplemented with 1% garlic extract for 4 weeks. After the 4 weeks feeding experiment, the artificial infection was made by V. anguillarum, S. iniae, E. tarda and VHSV. And the cumulative mortality was monitored for 2 weeks after artificial infection. The cumulative mortalities decreased in all experiments except for group of E. tarda compared to control group. We observed significantly higher levels of the hematocrit, glucose, total protein, lysozyme activity and the macrophage activity in the experimental group compared to the control group. In the experiments of drug sensitivity and MIC using the three bacteria (V. anguillarum, S. iniae and E. tarda), 1% garlic extract was more effective than the previously reported fermented garlic powder. These results suggested that garlic extract can increase the disease resistance of olive flounder against V. anguillarum, S. iniae and VHSV and the ability of nonspecific immune responses.