Pathology of Spontaneously Occurring Salmonellosis in Chickens
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Date
2024-03-02
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MAFSU, Nagpur
Abstract
The 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.