Isolation and identification of Edwardsiella tarda from the Cultured Red Sea Bream(Pagrosomus major) with Cryptocaryon irritans disease

The Cultured Red Sea Bream(Pagrosomus major) broke out a large number of deaths on the marine cage culture area of Donghan Town in Fuqing City during August in 2012. The fish got ill and finally died, with the symptoms of spleen and kidney enlargement, liver congestion in addition to Cryptocaryon irritans disease symptom on the body surface.With the help of TEM,biochemical characteristics of bacteria,and the molecular systematic(phylogenetic tree based on 16S rDNA sequences),the bacteria were identified.It was concluded that the bacteria isolated from the Red Sea Bream above,was Edwardsiella tarda, with the identity of 99%,and together with E.tarda in phylogenetic tree,what's more,with the same biochemical characteristics as E.tarda. The test result of the sensitivity to antibiotics showed that florfenicol and other nine antibiotics had the most inhibitive effects on the strain, while streptomycin and other three antibiotics had intermediate sensitive.