الفهرس 
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Abstract
Nowadays, fishes are considered a very important source of animal protein
for most of human beings. from this point, this study have been applied on 200
fishes of two different species represented as (100 Oreochromis niloticus and 100
Tilapia zillii) were collected randomly and examined freshly from Lake Temsah
and other sites in Ismailia governorate seasonally from (October, 2015 to
September, 2016).
This study was carried out for isolation and identification of the causative
agent of pseudomonas septicemia in different tilapia species (Oreochromis
niloticus and Tilapia zillii) in different seasons (Winter, Spring, Summer and
Autumn) using traditional and most advanced techniques (API 20E, VITEK 2
and PCR). In addition to, studying the antibiogramme of Pseudomonas
aeruginosa.
The obtained results revealed that:
1. The most clinical signs observed in naturally infected fishes
(Oreochromis niloticus and Tilapia zillii) were hemorrhages on body
surface especially at the ventral part of abdomen and around the vent,
exophthalmia, eyes cloudiness, vent prolapsed, scales detachment,
darkening of the skin and abdominal ascites.
2. The most common post mortem findings in diseased fished varied from
pale, congested and enlarged liver, spleen, kidney, intestine and gall
bladder beside, presence of ascetic fluid.
3. The isolated bacteria from naturally infected fished were identified as
Pseudomonas aeruginosa by using traditional and recent techniques (API
20E, VITEK 2 and PCR).
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4. The total prevalence of Pseudomonas aeruginosa in Oreochromis
niloticus was (40%) with the highest prevalence in winter (60%) followed
by autumn (44%) then spring (32%) while the lowest prevalence was in
summer (24%). It was isolated from liver, kidneys, spleen, intestine and
gills with the following percentage 75, 62.5, 45, 25 and 20% respectively.
The highest percent was from liver (75%) while the lowest was from gills
(20%).
5. The total prevalence of Pseudomonas aeruginosa in Tilapia zillii was
(22%) with the highest prevalence in winter (36%) followed by autumn
(28%) then spring (16%) while the lowest prevalence was in summer
(8%). It was isolated from liver, kidneys, spleen, intestine and gills with
the following percentage 72.7, 54.5, 31.8, 18.2 and 13.6% respectively.
The highest percent was from liver (72.7%) while the lowest was from
gills (13.6%).
6. VITEK 2 Compact (bioMerieux, France) is used for a rabid and accurate
identification of Pseudomonas aeruginosa in examined naturally infected
fishes (Oreochromis niloticus and Tilapia zillii).
7. PCR is sensitive, rapid and specific method to detect resistant genes
(MexA and MexB) and 16S rRNA gene in the selected isolates of
Pseudomonas aeruginosa.
8. The antibiogramme of Pseudomonas aeruginosa isolates showed that
they were sensitive to ampicillin, cefalexin, cefpodoxime, ceftiofur,
cefpirome, imipenem, amikacin, gentamicin and
trimethoprim/sulfamethoxazole. In addition to, they were intermediate
resistant to enrofloxacin, marbofloxacin and tetracycline. While, they
were resistant to amoxicillin, pipracillin, tobramycin and nitrofurantion.
9. The challenge test revealed that Pseudomonas aeruginosa isolated from
naturally infected fishes (Oreochromis niloticus and Tilapia zillii) were
Summary
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virulent to apparently healthy fishes used for experimental infection
showing the same clinical signs and post mortem lesions which were
detected in naturally infected fishes. The mortality rate in experimentally
infected fishes (Oreochromis niloticus and Tilapia zillii) with
Pseudomonas aeruginosa by I/P route representing 80% and 50% of the
total fishes, respectively.