Pseudomonas aeruginosa is an aerobic Gram- negative bacterium which has emerged as one of the most problematic nosocomial pathogens. To characterizes Pseudomonas aeruginosa strains that are wide spread in rabbits, 50 rabbit samples were collected from five different commercial private rabbit farms at Alexandria governorate showing symptoms of respiratory manifestation based upon culture methods coupled with biochemical tests, were used in this study. The results showed that, seven isolates of Pseudomonas aeruginosa recovered from 50 diseased rabbits with a percentage of 14% (two from lung, two from heart blood, one from liver, one from kidney and one from intestine), they were catalase, oxidase positive whereas negative for methyl red, Vogas proskaeur and indole; however; some of these methods are time consuming and may be not very accurate whereas API20E is rapid method which performs at least 20 different biochemical tests at once. To study the suscepaility of tested stains of Pseudomonas aeruginosa to 11 different antibiotics using disk agar diffusion the result showed that all Pseudomonas aeruginosa strains were highly sensitive to ciprofloxacin, tobramycin with sensitivity of 100% followed by cefazolin, amikacin, gentamicin and colistin sulphate with a percentages of 85.7%,71.4%,71.4%,42.85%, respectively. On the other hand, the isolates were highly resistant to amoxacillin, erythromycin and streptomycin and with an incidence of 100% for all, followed by chloramphenicol, trimethoprim –sulphamethaxazole (85.7% each) then, clostin sulphate, gentamicin (28.75% each) followed by amikacin 14.28%. In attempting to further identification of Pseudomonas aeruginosa strains at the DNA level, polymerase chain reaction (PCR) was used based on specific primer for oprL genes, the result showed that positive PCR as the agar gel electrophoresis of the PCR products showed that all them produced a DNA fragment or band at the 504 bp band. PCR has found to be rapid and more sensitive and specific in identification of Pseudomonas aeruginosa.
The lungs of all examined rabbits were congested, oedematous, scattered firm, yellowish areas of consolidated and indurated heamorrhagic areas. Multifocal necrosis presents in lung, liver, kidney and spleen. Microscopic examination demonstrated both parenchymal and bronchial changes .The lungs were extremely hyperemic and showed marked intrapulmonary heamorrhage and oedema, extensive mononuclear cell infiltration. Alveolar dilatation, septal wall destruction and lymphoid tissue hyperplasia. Pulmonary blood vessels were congested and surrounded by mononuclear cells infiltration. Bronchi and Bronchiolar walls were thickened by mononuclear cells infiltration. Epithelial degeneration with loss of bronchial cilia. The cellular infiltration include macrophages accompanied by lymphocytes with occasional plasma cells and multinucleated giant cells. The kidney showed degenerative changes in cortex and medulla, proliferation and accumulation of cells inside the Bowman's capsules and or contraction of the glomerulus. Renal tubules showed signs of degeneration, focal areas of necrosis. Liver showed congestion, hyperemia and widening of hepatic sinusoids. Extravasations of erythrocytes into the hepatic parenchyma. There was intercellular hemorrhage and distortion of hepatic cords and congestion in hepatoportal blood vessels. Spleen showed no separation between white and red bulb element, exhaustion of lymphocytes of hematopoietic element. Marked interstitial heamorrhage specially under splenic capsule.