Treatment of MAS caused by Aeromonas sobria in European seabass | ||
| Egyptian Journal of Aquatic Biology and Fisheries | ||
| Article 31, Volume 26, Issue 5, September and October 2022, Pages 535-556 PDF (1.53 M) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/ejabf.2022.264476 | ||
| Author | ||
| Magdy Khalil Soliman et al. | ||
| Abstract | ||
| Aeromonas sobria is one of the most common causes of motile aeromonas septicemia affecting fishes which results in substantial mortality and economic losses in the aquaculture sector. In the present study, Aeromonas sobria was isolated from a diseased Dicentrarchus labrax earthen pond with a high mortality rate. Hemorrhagic ulceration of the skin, cataract, fins and tail erosions together, with gill hemorrhage in a few cases, were the common clinical signs reported for naturally and experimentally infected fish. Severe congestion in internal organs, particularly the elementary tract, liver and posterior kidney in both naturally and experimentally infected fish were the dominant postmortem lesions. Thirteen A. sobria isolates were biochemically identified by the Vitek 2 system and then confirmed by the phylogenetic analysis. Pathogenicity test revealed that A. sobria was virulent for D. labrax fingerlings with LD50 equals 2.64 × 107 CFU. Fish-1. Histopathological examination indicated the presence of severe degenerative changes in the liver and kidney of experimentally infected D. labrax such as inflammation, necrosis, mononuclear cell infiltration, melano-macrophage centers activation. Doxycycline was the most effective antibiotic against all of the tested isolates, followed by flumequine (77%) and oxytetracycline (69%), while most A. sobria isolates were resistant to cephradine as only 15.3% of the isolates were susceptible while all isolates showed complete resistance to amoxicillin. The treatment trial indicated the efficacy of infeed administration of doxycycline at a dose of 20 mg. kg-1 bodyweight in decreasing fish mortality to half, but the higher dose (40 mg. kg-1 bodyweight) was more effective in termination of A. sobria infection in challenged D. labrax fingerlings. | ||
| Keywords | ||
| Vitek; Sequencing; Histopathology; Doxycycline; Dicentrarchus labrax | ||
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