This report details findings of an investigation into complaints by commercial fingerling producers of low-grade mortalities, poor reproductive success, emaciation, skin lesions, and severely arched backs among broodstock of channel catfish Ictalurus punctatus. Gross lesions involved the jaw, fin bases, and vertebral column. Jaw and fin lesions consisted of small hemorrhagic ulcers and exudate-filled tracts that communicated with underlying joints and destroyed their articular surfaces. Spinal changes, recognized grossly by severe arching of the proximal vertebral column, resulted from the collapse and displacement of vertebral bodies, causing compression of the spinal cord. Affected vertebrae were lysed by pyogranulomatous inflammation that infiltrated into adjacent muscle and the spinal canal. A Streptococcus-like organism was visualized in exudate and isolated repeatedly from lesions, but only once from the kidney of a single fish. Preliminary analysis of a 16S ribosomal DNA sequence showed a close relationship to S. iniae, S. parauberis, and S. canis. Koch's postulates were fulfilled after challenge with and reisolation of the agent from identical lesions that appeared at fin bases at 2 weeks postinjection. Historical evidence and gross and microscopic findings imply the presence of a pathogen of low virulence that is capable of producing severe localized infections after a brief period of septicemia. The disease presents as a chronic debilitating syndrome that is sufficient to inhibit mobility, feeding, and reproductive activity in affected fish. Complete biochemical and molecular characterization of the bacterium (published elsewhere) has established the agent as a novel species, S. ictaluri.

中文翻译：

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鲶鱼亲鱼中的链球菌 ictaluri关节炎、骨质溶解、肌炎和脊髓性脑膜炎

本报告详细介绍了对商业鱼种生产者投诉的调查结果，这些投诉涉及沟鲶 Ictalurus punctatus 亲鱼的低死亡率、繁殖成功率低、消瘦、皮肤损伤和严重拱背。大体病变涉及下颌、鳍基和脊柱。颌骨和鳍部病变包括小的出血性溃疡和渗出液，它们与下面的关节相通并破坏了它们的关节面。脊柱变化，通过近端脊柱的严重弓形粗略识别，是由椎体塌陷和移位引起的，导致脊髓受压。受影响的椎骨被渗入邻近肌肉和椎管的脓性肉芽肿性炎症溶解。在渗出液中观察到一种链球菌样生物，并从病变中反复分离，但仅从一条鱼的肾脏分离一次。16S 核糖体 DNA 序列的初步分析显示与 S. iniae、S. parauberis 和 S. canis 密切相关。Koch 假设在注射后 2 周出现在鳍基部的相同病变中攻击和重新分离药剂后得到满足。历史证据以及肉眼和显微镜发现表明存在一种低毒力病原体，在短暂的败血症后能够产生严重的局部感染。该疾病表现为一种慢性衰弱综合征，足以抑制受影响鱼类的活动、摄食和繁殖活动。