الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 153 |  |  |
| | | from | 153 | | |
Abstract
In this study total of (240) Oreochromis niloticus species were collected randomly and monthly during an outbreak of disease from different fish farms in the areas of Bahr El-Baqar, El-Sharkia governorate. Clinical signs and postmortem lesions of affected Oreochromis niloticus were recorded. The most isolated bacterial agent was Aeromonas veronii biovar sobria which identified using Vitek 2 system and traditional method as Aeromonas sobria. The identification was confirmed by detection of 16s rRNA gene by PCR then sequencing of this gene and by analysis of sequence result identified as Aeromonas veronii. The prevalence of the was 86.25% in the four months, with highest prevalence in July 95% followed by August 91.67% and June 86.67% then may 71.67% . The experimental infection was studied with dose of 1.2x108 cells/ml and the mortality was 70 and 35% of the I/p and I/M respectively. The virulence of bacteria was detected by detection of hemolytic activity on blood agar and detection of hemolysin gene using PCR. The bacteria according to Vitek 2 system was sensitive Meropenem, Tigecycline, Trimethoprim + Sulphamethoxazol, Ciprofloxacin, Moxifloxacin, Gentamycin, Tobramycin, Cefepime, Imipenem, Amikacin while it has intermediate sensitivity to Ceftriaxone. On the other side it was resistant to Aztreonam, Nitrofurantion, Cefazolin, Ampicillin, Ampicillin/Sulbactam.