Histopathological changes of Serratia rubidea isolated from cattle in mice

Abstract

The research conducted to isolate and identify the opportunistic pathogen Serratia rubidaea from other similar species using mice models for S. rubidaea infections. 100 fecal samples were taken from cattle in Baghdad City which were identified by biochemical tests, Vitek 2 compact, and PCR analysis, then sequencing for 16S rRNA. Twenty-four albino mice of both genders were divided into three groups: infectious and control. The first group infected with 1.5×10⁸ cfu. (0.1ml\orally), the second group infected with 3.0×10⁸cfu (0.1ml\orally), and the third group as negative control were injected with 0.1ml PBS. To characterize infection in mice numerous criteria were employed including clinical signs, mortality, and histological changes. From the collected fecal samples, 12 (12%) of the Serratia isolates were isolated using culture media, the isolates were positively identified as 99% S.rubidea using Vitke 2, and 98% by sequencing when matching with GenBank references was found registered the bacterial isolate with accession No. (OR757107.1). The histopathological changes of the intestine showed degenerative changes in the submucosal glands, cystic dilation, and inflammatory cell infiltration.  while kidney exhibited vascular congestion, dilation of vessels, cellular swelling of the tubular epithelial lining, interstitial hemorrhage, and glomerular capillary congestion, and liver showed inflammatory cell infiltration around hepatic vessels, narrowing of hepatic sinusoids, focal hepatic necrosis with mild inflammation, perivascular inflammation, portal vein dilation, and periductal inflammatory infiltration. Finally, spleen displayed congestion in the red pulp, lymphoid depletion in the white pulp and splenic follicles, and scattered megakaryocytes. Some splenic follicles showed variation in size