RESUMO
Field problem in a governmental horse farm accompanied with a fever, acute colitis and diarrhea was investigated. A total, 58 fecal samples, 7 samples obtained from horses suffering from acute colitis and diarrhea and 51 fecal samples from horses had mild diarrhea. Bacteriological examination of 7 samples revealed isolation of Salmonella Newport, Escherichia coli, Klebsiella oxytoca and Proteus species with an incidence of 85.7%, 42.9%, 28.6% and 14.3% respectively while examination of 51 fecal samples obtained from horses had mild diarrhea revealed isolation of E. coli, Pseudomonas aeruginosa, Klebsiella oxytoca, Citrobacter freundii, Proteus species Kiebsiella pneumoniae and Salmonella Newport with an incidence of 86.3%, 39.2%, 29.4%, 25.5%, 21.6%, 11.8% and 2%, respectively. Serological identification of Salmonella species and E. coli were carried out. Salmonella enterica serotype Newport was recovered from 6 out of 7 horses suffering of acute colitis and diarrhea while it could be isolated from a horse had mild diarrhea. Salmonella Newport was isolated from the colonic mucosa and mesenteric lymph node of 2 dead horse. No Salmonella species could be isolated from feed and water. Analysis of the questionnaires showed access to new arrival the source of Salmonella excretion on horse farm. An experimental approach to control spreading of S. Newport by using a prepared S. Newport autogenous bacterin was evaluated in mouse model. Immunogenicity and protection studies against S. Newport challenge were performed in Balb/C mice. Mice were immunized I/M and S/C with 2 doses of an autogenous bacterin. Antibody responses were determined by enzyme-Linked-immunosorbent assay [ELISA]. Also, non-specific immune responses including nitric oxide production [NO], catalase activity and hydrogen peroxide release [H[2]O[2]], have been measured. Immunization of mice with the autogenous bacterin resulted in a significant enhancement of humoral response following to vaccination and challenge as compared to control group. Additionally, this immunization succeeded in raising NO production, activating catalase and increase H[2]O[2] release. Increasing survival was noticed in immunized mice [80% and 66.7%] being declined in challenged non-immunized group [6.7%]. It was concluded that the prepared autogenous S. Newport bacterin could elaborate not only humoral immune responses but also host innate responses against S. Newport. However, more studies should be conducted under field condition to evaluate the efficacy of vaccine