Salmonella infections are a frequent cause of systemic pathologies in poultry production. This also includes the nervous system, the impact of which has hardly been studied.
Therefore, a study was carried out that aimed to detect an alternative pathogenic pathway in the invasion of brain tissue in chickens by Salmonella spp. Brain infection produces neurological symptoms and Salmonella strains isolated from brain tissue showed the presence of two virulent genes. Verification of the route from the intestinal mucosa through the blood-brain barrier was achieved by experimental infections in day-old chicks free of specific pathogens, through two routes of inoculation.
Salmonella spp. of five flocks of chickens showing central nervous system symptoms by serotyping and antimicrobial testing. Virulence profiles were described using the detection of the virulence plasmid spvC and the Salmonella plasmid sopB. A pathogenicity study of isolates in day-old chickens free of specific pathogens by oral and intracerebral administration was carried out, and experimental infection in embryonated chicken eggs free of specific pathogens by intra-vitelline and intra-allantoic administration was investigated. Histopathology and immunohistopathology against Salmonella antigen were also performed in brain tissue.
Three isolated serotypes
Three Salmonella serotypes were isolated from the brains of five batches: two from Salmonella Virchow, two from Salmonella Kentucky, and one from Salmonella Enteritidis. The sopB gene and the spvC plasmid-mediated operon were identified in all isolated strains. Salmonella strains were re-isolated and identified in the brain and internal organs of post-experimental infected chickens. The infected chicks showed nervous symptoms associated with Salmonella infection. The presence of Salmonella antigens in the staining of brain tissues also indicates penetration of the blood-brain barrier.
In conclusion, the results of this study indicate that some virulent systemic strains of Salmonella spp. can induce symptoms in the central nervous system of affected chickens.
Heba Badr, Mohamed A. Soliman and Soad A. Nasef. Bacteriological and molecular study of Salmonella species associated with central nervous system manifestation in chicken flocks. Veterinary World, 13(10): 2183-2190. doi: www.doi.org/10.14202/vetworld.2020.2183-2190