Isolation and identification of a pathogenic Plesiomonas shigelloides from diseased grass carp

Abstract:

Abstract:［Objective］The aim of this study is to identify strain JX-09 and confirmed that the strain is the pathogen of diseased grass carp (Ctenopharyngodon idellus).［Methods］A pathogenic strain JX-09 was isolated from the diseased grass carp. The strain was identified based on physiological and biochemical characteristics，and the sequence analysis of 16S rRNA．Virulence of strain JX-09 to healthy grass carp was also tested．Furthermore，drug sensitivity was detected with Kirby-Bauer’s agar diffusion method．［Results］ Strain JX-09 was identified as Plesiomonas shigelloides by biochemical analysis and molecular biology．The P．shigelloides strain was re-isolated from the artificial infected grass carp，and the LD50 was about 6.4×104 cfu/g．Drug sensitive tests showed that strain JX-09 was susceptible to aztreonam，cefazolin，cephalothin and ceftriaxone，and resistant to kanamycin， medicamycin，vancomycin and piperacillin．［Conclusion］Strain JX-09 was the pathogen of grass carp with muscle erosive disease．To the best of our knowledge，this is the first report that P．shigelloides as the pathogenic strain of grass carp.