The Pathogeny Isolation And Identification And Histopathology Of Bacterial Septicemia In Channel Catfish

In recent years, in Hunan Zhexi reservoir and Fengtan reservoir, etc.one after another occurred a acute and contaminating epidemic bacterial septicemia hazard the health of Channel Catfish in cage breed, has brought serious economic loss to the local channel catfish farming, a serious threat to the healthy development of channel catfish aquaculture industry. This experimentation was studied on its pathogen isolation, purification, identification and histopathology, with the aim at pathogen characteristics and pathological changes, provide a theoretical basis for a better control to the spread of the disease in aquaculture production.Separate three pathogenic strains (FBI,FB2, FB3)from the intestines, liver, kidney, stomach of the typical symptoms bacterial septicemia which infected channel catfish, Throught experimental infection confirmed FBI was the pathogen of bacterial septicemia for the catfish. On the strain of their physiological and biochemical characterization initially identified FBI as Aeromonas hydrophila. In succession use means of molecular biology to identify FBI,the results show that the 16S rDNA sequence of bacterium have the highest homology with Aeromonas hydrophila. So to the molecular biology level identy this bacteria as Aeromonas hydrophila. The results of drug sensitivity test showed that:Aeromonas hydrophila have a highly sensitive to the compound sulfamethoxazole, florfenicol, norfloxacin, gentamicin, azithromycin tobramycin and other, tetracycline, doxycycline, neomycin, streptomycin, lomefloxacin and other moderately sensitive, low sensitivity to amikacin, have great resistance to penicillin, vancomycin, midecamycin, cefazolin, cefoxitin and so on.Healthy channel catfish which infectde Aeromonas hydrophila showed the lesions on surface hyperemia, hemorrhage, enlarge abdomen, abdominal cavity filled with ascites, intestinal mucosa hyperemia, hemorrhage. The mainly pathological changes of bacterial septicaemia in Channel Catfish were systemic edema, cell swelling, denaturalization, necrosis and loss, the most serious injury was the liver, intestine, kidney, stomach. Its were the major damage target organ. Physiological and biochemical of blood test results show that the activity of glutamic pyruvic transaminase and glutamic oxaloacetic transaminase were significantly increased by 300%-500% in the serum of ill channel catfish.The content of total protein, albumin, globulin increased 80% to 200%. Ammonia levels soraed 200% to 300%.Creatinine, total bile acid decreased,uric acid decreased significantly to little.