Efficiency and characterization of an antibacterial substance from (Origanum vulgare) against Aeromonas hydrophila in some freshwater fishes [electronic resource].

Includes references.

This stUdy was applied to isolate and identify Aeromonas hydrophila which is causative agent of Motile Aeromonas septicemia (MAS) in freshwater fishes (Oreochromis nilotli:us and Clarias gariepinus) and to study the efficacy and characterization of an antibacterial agent from (Origanum Vulgare) against Aeromonas hydropMa in vitro which is causative agent of (MAS). This study was applied on 100 O. niloticus weighted 80 ± 5 g and 100 C gariepinus weighted 150 ± 5 g 0. niloticus were suffering from lose of appetite, lethargic, swim near to the water surface, hemorrhage at the fins bases ulcer behind the head roughness of scales (bristle out), slight distended abdomen and redness of anal opening. Internally. the fish had distended gall bladder, enlarged kidney and accumulation of serious fluid in abdominal cavity. While C gariepinus showed hemorrhage, erosion and ulcer on different area of the body specially the lateral and ventral parts of the body. Internally, there were congested liver, kidney and spleen with hemorrhage is peritoneal caVity and the intestine was free from any food particles. The bacteriological examination of samples taken from clinically affected fishes revealed the isolation of Aeromonas hydrophila . The incidence of infection in O. niloticus reach 58% but in C gariepinus was 45% with a total percentage in both fishes 51.5%. The experimental infection with the isolated Aeromonas hydrophila intraperitoneally resulted in 90% mortality in O. niloticus and 80% mortality in C gariepinus. The antibiogram sensitiVity test showed that ciprofloxacin in a dose 5mg is highly effective in control of Aeromonas hydrophila. The separation of the active ingredient and its purification was perfonmed using both thin layer chromatography (TLC) , and column chromatography techniques. The physico-chemical characteristics of the purified antibacterial agent viz. color, melting point, solubility, elemental analysis, spectroscopic characteristics and assay of total phenolics have been investigated. The active extract of Origanum vulgare a suggested empirical formula of C11 H19 D8N was evaluated as antibacterial agent against A. hydrophila organism.

Summary in Arabic.

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