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Updated: Aug 14, 2026

Catheterization of Intestinal Loops in Ruminants
Published on: June 11, 2009
Fatal cases of Citrobacter freundii septicemia and encephalitis in sheep
Huisheng Liu1,2, Zhanqin Zhao1,2, Yun Xue1,2
1Laboratory of Animal Infectious Diseases and Microbiology, College of Animal Science and Technology (Liu, Zhao, Y Xue, Q Xue), Henan University of Science and Technology, Luoyang, China.
Abstract:
Citrobacter freundii is considered a ubiquitous organism and an opportunistic pathogen. Reports of C. freundii-associated disease in mammals have been very limited. We report an outbreak of C. freundii septicemia and encephalitis in sheep, with a high mortality rate; 13 adult sheep were found dead over a 6-d period on a farm in central China that housed ~1,370 sheep. Three animals were autopsied and showed septicemia, congestion of meningeal vessels, and pleural effusion. C. freundii was isolated in abundance in pure culture from 19 of 21 organs. All 3 C. freundii isolates had similar antimicrobial resistance phenotypes for 10 of the 11 agents tested, and were sensitive to 8 of the 11 agents. We reproduced C. freundii infection in sheep experimentally by oral or subcutaneous inoculation routes, and recovered the challenge organism from all of the experimentally infected sheep. Intramuscular injection of enrofloxacin protected sheep against an otherwise fatal challenge. Our results suggest that C. freundii played a major role in this disease outbreak.
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