Isolation and identification of Yersinia ruckerifrom hybrid sturgeon and pathological lesions of its infection

Objective  To explore the etiology of a serious infectious disease occured in hybrid sturgeon (Acipenser schrencki ♀ × A. baeri ♂) from a farm of Qionglai, Sichuan Province.

Method  The pathogens were isolated from the liver, spleen and kidney tissues of diseased fish, and identified by physicochemical characteristics, 16S rRNA and gyrB gene sequences analyses, meanwhile the susceptibility test and histopathological observation were performed.

Result  One gram-negative predominant bacteria strain (YC160412) was isolated and identified as Yersinia ruckeri by physicochemical characteristics, 16S rRNA and gyrBgene sequences analyses. The antibiotic susceptibility test showed that the pathogen was sensitive to cefazolin, ampicillin, florfenicol, and resistant to amoxicillin and erythromycin. Histopathological observation found that Y. ruckeri infection caused significant damages to hybrid sturgeon multiple organs, especially in liver, spleen, kidney, intestine and gill. The main pathologic lesions were obvious degeneration, necrosis, hemorrhage and infiltration of the inflammation cells. The pathogen was largely found in liver, spleen and kidney tissues.

Conclusion  This study confirms Y. ruckeri is the pathogen of the epidemic. Its infection can cause multiple organ dysfunctions and even death of hybrid sturgeon.