الفهرس 
AbstractOnly 14 pages are availabe for public view
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Abstract
In this study a total number of 655 samples were obtained from 117 different farms (breeder, layer, baby chicks and hatcheries) located in Giza, Qaliobya and Dakahlia Governorates from 2013 to 2015, the samples were collected under complete aseptic condition. The samples obtained from chickens suspected to be died due to avian salmonellosis. Incidence of Salmonella spp. was 2.13% (14/655). Serotyping of isolated salmonellae were S.Typhimurium, S.Enteritidis, S.hindmarsh, S.amersfoort, S.cremieuz, S.newport, S.heistopdenberg, and S.Agona. Ten of the isolated salmonella serovars were screened for different virulence genes (invA, pefA, mgtC, avrA, spvC, sopB and stn) by PCR. invA gene was detected in all isolates except one isolate in a percentage of 90%, avrA, stn genes were detected in eight isolates in a percentage of 80%, mgtC, sopB genes were detected in six isolates in a percentage of 60%, and spvC, pefA genes were not detected in any isolates in a percentage of 0%. There is variation in virulence gene profiles between strains belonging to an individual serovar. Ten of the isolated salmonella serovars were tested for antibiotic sensitivity, the tested strains were found to be 100% resistant to Tetracycline, Sulphamethoxazole and Ampicillin, also were 90%, 80%, 70% resistant to Doxycycline, Amoxicillin, and Ceftazidine respectively. Also 40%, 50% of isolated serovars were found to be sensitive to Chloramphenicole and Enrofloxacin respectively. There were relations between the virulence gene invA, avrA, stn and resistance pattern of isolated salmonellae to Tetracycline, Ampicillin, Sulphamethoxazole, Doxycycline and Ceftazidine. By using vero cells on tissue culture to test invasion ability of ten of the isolated salmonella serovars, Cytopathological changes on tissue culture were observed under the inverted microscope after 12 hour post infection and found cell vaculation, irregular in shape and 25% of monolayer sheet destroyed by S.Amersfoort, S.Agona and S.Typhimurium, also cell detachment and more than 50% of monolayer sheet were destroyed by S.Newport, S.Hindmarsh, s.cremieuz and S.Enteritidis, more than 70% of monolayer sheet were destroyed by S.Heistopdenberg and S.Enteritidis and 100% complete destruction of cell and monolayer sheet in S.Newport. The study aims to explore the current situation of Salmonellae in poultry farms in Egypt, so detection of Salmonella in chicken needs a greater concern for effective control programs in poultry farms and the epidemiological surveillance of this serovars would be necessary to evaluate its possible impact on human health, particularly in Egypt and other countries.