Ingole, R. S.Akare Isha Pramod2024-11-042024-11-042024-03-02https://krishikosh.egranth.ac.in/handle/1/5810216006The present study investigated the isolation and identification of Salmonella and spontaneous pathology of salmonellosis in chickens. Total 212 dead birds, comprising of broilers, layers and backyard birds in and around Akola were considered for the present investigation. Liver tissue and intestinal content were obtained aseptically from each bird for cultural, biochemical, morphological and molecular confirmation of Salmonella. On cultural examination, out of 212 birds, 28 were found positive for Salmonella. PCR confirmation revealed overall occurance of 75% for Salmonella spp. Total 75% samples were positive for S. Gallinarum using the ratA gene primer by PCR. Multiplex PCR analysis revealed 58.33% samples positive for S. Typhimurium (Flic-C) and 8.33% samples positive for S. Enteritidis (IE-1). Presence of the invA, iroB and stn virulence genes detected in all Salmonella isolates, while none of the isolates contained the spvC and spvR genes. AST showed higher degree of sensitivity to amikacin and piperacillin-tazobactam while trimethoprim and ampicillin showed resistance. Additionally, 24 phenotypically ESBL positive Salmonella isolates were further analyzed for the distribution of ESBL genes using multiplex PCR. The results showed all samples were positive for the blaTEM gene, followed by 37.5% for blaSHV, 25% for blaCTX-M and none of the samples were positive for blaOXA. Gross pathological examinations of Salmonella-infected birds showed swollen liver and spleen along with multiple necrotic foci on the liver, pinpoint hemorrhages on the spleen and congestion in intestine, kidneys, lungs and heart. Microscopic observations revealed diffuse necrosis, granular and vacuolar changes in the liver, desquamation of tubular epithelium, degenerative changes in the kidneys, necrosis of bronchiolar wall epithelium in the lungs and myocardial degeneration in the heart. Additionally, the spleen exhibited depletion of lymphoid cells, while the intestine showed infiltration of inflammatory cells into the lamina propria, along with atrophy of intestinal glands and degenerative changes.EnglishThesis