Bacteriological and molecular study of species associated with central nervous system manifestation in chicken flocks.

Background And Aim: species often cause systemic health problems in poultry flocks, sometimes including nervous systems manifestations. This impact of has rarely been studied. This study aimed to define an alternative pathogenic pathway for spp. invasion of brain tissue in chicken flocks. Brain infection produces neurological manifestations; strains isolated from brain tissue showed the presences of two virulence genes. Confirmation of the pathway of isolates from intestinal mucosa through the blood-brain barrier was attained using experimental infections in specific pathogen-free (SPF)-day-old chicks through two routes of inoculation.

Materials And Methods: Isolation of spp. from five chicken flocks that showed signs of the central nervous system (CNS) effects were isolated. Isolates were characterized by serotyping, and antimicrobial assays. In addition, virulence profiles were described using detection of virulence plasmid , and plasmid . A pathogenicity study of isolates in specific pathogen-free (SPF)-day-old chicks through oral and intracerebral administration performed, and experimental infection in SPF embryonated chicken eggs through intra-yolk and intra-allantoic administration was investigated. Supporting histopathology and immunohistopathology against antigen in brain tissue were performed for flock and experimental infections.

Results: Three serotypes of were isolated from the brains of five flocks (two Virchow, two Kentucky, and one Enteritidis isolates). Phage related gene and plasmid-mediated operon were identified in all isolated strains. The strains were re-isolated and identified from the brain and internal organs of post-experimental infected chicks. Infected chicks showed nervous manifestations associated with infection. The presence of positively stained antigen in brain tissues indicates penetration of the blood-brain barrier by the species.

Conclusion: Our results indicate that some virulent systemic strains of spp. can induce CNS manifestations in chicken hosts.