Background: Enterobacter hormaechei is typically a opportunistic pathogenic bacterium in humans, and no pathological change of of Enterobacter hormaechei in diseased sheep has previously been documented.
Case presentation: Three free-range, four-month-old female sheep were ill with respiratory disease and died three days after receiving treatment with ceftiofur sodium. A frozen lung sample of one sheep was studied using bacterium isolation, and lung samples of the other two sheep were collected and analyzed by histopathological examination and bacterium isolation. The 16S rRNA gene sequences and biochemical characteristics of the isolates were analyzed. All results showed the isolated strain to be Enterobacter hormaechei. Phylogenetic analysis of the 16S rRNA sequence showed three representative strains were most closely related to the strains isolated from calf. Antimicrobial sensitivity tests indicated that no sensitivity to the β-lactam antimicrobials involved in treatment of sheep respiratory disease in China. Detection of the genes responsible for β-lactam resistance showed that all three isolates from sheep harbor blaSHV and blaKPC. Interstitial pneumonia, bronchial epithelial cells shedding, and massive mucous secretion were observed in the lung histopathological sections. Immunohistochemical staining showed that specific staining was mainly limited to the alveoli and alveolar septum.
Conclusions: This appears to be the first report of pathological changes in lungs of sheep with respiratory disease and death associated with Enterobacter hormaechei.
Keywords: Drug resistance; Enterobacter hormaechei; Immumohistochemical staining; Respiratory disease; Sheep.
© 2022. The Author(s).