Isolation and Identification of Staphylococcus saprophyticus from Diseased Hybrid Sturgeon

Hybrid sturgeon is an important economic fish species in China. In 2021, a bacterium was isolated from the liver and kidneys of freshwater-farmed hybrid Yichang City, Hubei Province, causing disease with high mortality surface bleeding. Through morphological observation, 16S rDNA gene sequence analysis, pathogenicity, antimicrobial sensitivity test, as well serum physiological biochemical it identified Staphylococcus saprophyticus named E702. The E702 highly homologous to S. GenBank. Phylogenetic analysis showed that clustered into one clade. 50% lethal dose 2.14 × 105 CFU/g. percentages monocytes eosinophils were markedly increased diseased sturgeon’s blood, whereas platelets lymphocytes decreased. activity levels aspartate aminotransferase, alanine aminotransferase alkaline phosphatase significantly increased. suffered obvious damage many tissues organs, especially kidney, showing swelling, hyperemic inflammatory cell infiltration. sensitive antibiotics such neomycin, cefazolin, norfloxacin, carbenicillin, gentamicin ciprofloxacin. study not only proved responsible for great deal deaths, but also shed light on its potential risks farming. research results provided theoretical basis diagnosis prevention this disease.