Thesis (M.Sc.) - Cairo University - Faculty of Veterinary Medicine - Department of Animal Diseases

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

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