Studies On Pathogenic Bacteria Identification And Hemopathology Of The Exophthalmic Disease In Epinephelus Septemfasciatus

A pathogenic bacterial strain CB1008 was isolated from the eyes and internal organs of sevenband group(Epinephelus septemfasciatus).It was proved to be the pathogen of the sevenband group by the artificial intramuscular and abdominal cavity infection experiment, and the LC₅₀ of the bacterium to sevenband group were 3.78×10⁶CFU/ml and 5.98×10⁶ CFU/ml.Morphological observation showed that it was a short-rod and Gram-negative bacterium with single polar flagella.According to API-32E system,traditional physiological and biochemical experiments and 16S rDNA gene homology comparison of the bacteria,The results showed the reisolated strain CB1008 belongs to Vibrio harveyi.The test of sensitivities of strain CB1008 to 36 kinds of antibiotics revealed that the pathogen was sensitive to chloramphenicol,nalidixan,tetracycline,norfloxacin,and fleroxacin.The blood physiological and biochemical indices were examined to the Exopht- halmic disease of sevenband group.Compared with healthy fishes,The results showed that the number of red blood cells[(1.42±0.37)×l0⁹ind/ml]and white blood cells[(1.05±0.44)×10⁷ ind/ml],and contents of hemoglobin(96.60±11.50g/L),total bilirubin(0.86±0.29μmol/L), total protein(14.23±1.91g/L),calcium decreased(3.48±0.25mmol/L),but the contents of red blood cell brittleness[(0.32±0.07)%NaCl],urea nitrogen(0.77±0.30mmol/L),creatinine (14.80±9.60μmol/L),uric acid(2.30±1.06μmol/L),Potassium(3.64±0.27mmol/L), magnesium(1.52±0.08mmol/L),chlorine(161.63±5.15mmol/L) and serum enzymes of ALT (4.60±3.53U/L),AST(21.20±13.21U/L),LDH(199±156.42U/L),ALP(94.6±28.66U/L),γ-GT(4.80±3.88U/L) increased.These results indicated that the Vibrio harveyi was strongly opathogenetic and the liver,kidney,muscle of the sevenband group had diseased and many important physiological functions were seriously destroyed,after sevenband group was infected.Vibrio harveyi is a kind of pathogenic bacterium commonly found in aquaculture disease, but this is the first time that Vibrio harveyi is reported as the pathogenic bacteria of sevenband grouper in China,in order to provide reference in health management and disease control.