白斑狗鱼“败血症”病原及组织病理研究

Studies on the pathogen and histopathology of septicemia in Esox lucius

2003年3月和2004年4月,新疆某养殖场和西安灞桥区某养殖场的白斑狗鱼(Esox luciusLinnaeus)相继爆发“败血症”。从具有明显症状的濒死病鱼体表病灶和内脏组织分离得到12株优势菌株,经人工感染试验表明:其中10株分离菌为致病菌。对分离菌株进行形态、培养特征、生理生化试验鉴定,认为该病原菌为杀鲑气单胞菌史氏亚种(Aeromonas salmonidasubsp.smith)。血清学试验表明各分离菌株具有相同的保护性抗原。组织病理学研究表明:患病狗鱼病灶肌纤维明显肿胀断裂,肌纤维束之间出现间隙;肝胰组织严重坏死,细胞核溶解消失,细胞浆崩解;肾小管绝大部分均已坏死,细胞破裂,胞浆呈红色团块状流失于管腔。脾脏细胞大量坏死,髓质内含铁血黄素沉积。代表菌株EL0304-1药敏试验结果为:对供试24种抗菌药物中的磺胺二甲嘧啶钠、磺胺二甲唑钠等不敏感;庆大霉素、卡那霉素等中度敏感;对氧氟沙星、培氟沙星、新霉素等高度敏感。

The white spot pike Esox lucius Linnaeus were infected with septicemia in fishing farm in Novenmber 2003 and Apirl 2004 in Xi＇an Area of Shanxi Province and Shihezi Area of Xiangjiang regional autonomy. 12 strains of bacteria were isolated from the diseased fish with the typical septicemia symptom. 10 strains were confirmed to be the pathogens of the white spot pike by artificial infection test. All of these strains have the same morphological features, physiological and biochemical characteristics that were very similar to those of Aeromonas salmonida subsp, smith. The serum test showed that they had the same serum type. The histopathology researches were conducted to analyze the mechanisms of the disease organs samples such as mucles, hepatopancreas, kidneys and liens which were collected from disease pikes. Results showed that the muscle fibers were swelling and fractured, fiber bundles were separated from each other; The hepatopancreas cells necrocytosis significantly serious, the nuclear were karyolysis and disappeared, the cytoplasm were buist; The most of kidney canalicules were necrocytosis, the cytoplasma meinbranes were broken down and filled with cytoplasm; The most cells of lien necrocytosis and lots of hemosiderin cumulated in it. Meanwhile, chosen the representative strain EL0304-1 to medicine senitivity test, the sensitivity of the swain to 24 kinds of antimicrobial agents were detected. The results indicated that it was high sensitive to Ofloxacin, Pefloxacin, Neomycin etc. ; The Gentamycin, Kanamycin, etc. also showed good antibiotic performance; While the Sulphadimidine sodium, Sulphamethizole sodium etc. had no inhibitory activity to the swain.