Author(s): Mai AM El-Son, Nevien KM Abdelkhalek, Ahmed MM El-Ashram and Viola H Zaki

Abstract: This study was focused on detection of the main causes of mass mortalities in Al-manzala fish farms in Dakahlia governorate during disease outbreaks in the summer season of 2018. Four hundred Oreochromis niloticus (Nile tilapia) were collected randomly from semi-intensive earthen ponds. The clinical signs and postmortem lesions were recorded. Phenotypic characterization, biochemical detection and sensitivity testing of the obtained strains to various antibiotics were applied. The results revealed that 175 Aeromonas species were isolated from the examined fish, whereas A. hydrophila was the most prevalent strain (57.1 %). A. hydrophila was isolated and identified by the API 20 E system. The experimental infection using the isolated A. hydrophila to detect the virulence of the strain recorded 60 % of mortality rate. Regarding the antibiotic sensitivity test, A. hydrophila isolate was sensitive to Aztreonam, and resistant to Amoxicillin, Ampicillin, Streptomycin, Cefotaxime, and Erythromycin. It can be concluded that Aztreonam can control A. hydrophila infection in tilapia farms.

Pages: 197-202  |  885 Views  187 Downloads

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