Engineering Research Center of Ecology and Agricultural Use ofWetland, Ministry of Education, Yangtze University, Jingzhou, 434024, China.
Guangdong Provincial Key Laboratory of Aquatic Animal Disease Control and Healthy Culture, Guangdong Ocean University, Zhanjiang, 524008, China.
Microb Pathog. 2022 Dec;173(Pt A):105818. doi: 10.1016/j.micpath.2022.105818. Epub 2022 Oct 7.
Chinese sturgeon (Acipenser sinensis) is an indigenous species of China and is listed as a critically endangered species. Recently, second filial generations of Chinese sturgeon in the Yangtze River Fisheries Research Institute suffered from a severe disease. In this study, two kinds of pathogenic bacteria were isolated from diseased sturgeon and identified as Plesiomonas shigelloides and Citrobacter freundii, based on 16S rDNA gene sequence alignment analysis. Antimicrobial susceptibility testing showed that P. shigelloides was resistant to ampicillin, penicillin, midecamycin, oxacillin, and clindamycin; and sensitive to tocefatriaxone, piperacillin, cefoperazone, cefazolin, and ciprofloxacin. C. freundii was resistant to ampicillin, penicillin, midecamycin, oxacillin, and clindamycin; and sensitive to chloramphenicol, cefuroxime, norfloxacin, ciprofloxacin, and ceftazidime. The median lethal dose (LD) values of P. shigelloides and C. freundii were 4.50 × 10 colony forming units (CFU)/g and 3.20 × 10 CFU/g, respectively. Clinical symptoms of challenged sturgeons were the same as those of naturally infected sturgeons. Histopathological examination disclosed severe damage in the viscera of P. shigelloides and C. freundii-infected sturgeons. This is the first report suggesting that P. shigelloides infection is associated with mortality of Chinese sturgeon. The results of this study revealed the pathogenesis and severe pathogenicity of P. shigelloides and C. freundii in cultured Chinese sturgeon, and offer insights into the prevention and treatment of bacterial infection caused by P. shigelloides and C. freundii in cultured sturgeons.
中华鲟（Acipenser sinensis）是中国的特有物种，被列为极危物种。最近，长江水产研究所的中华鲟第二代鱼苗遭受了一种严重的疾病。在本研究中，从患病的中华鲟中分离出两种病原菌，基于 16S rDNA 基因序列比对分析，鉴定为痢疾志贺菌和弗氏柠檬酸杆菌。药敏试验结果显示，痢疾志贺菌对氨苄西林、青霉素、麦迪霉素、苯唑西林和克林霉素耐药；对头孢噻肟、哌拉西林、头孢哌酮、头孢唑林和环丙沙星敏感。弗氏柠檬酸杆菌对氨苄西林、青霉素、麦迪霉素、苯唑西林和克林霉素耐药；对氯霉素、头孢呋辛、诺氟沙星、环丙沙星和头孢他啶敏感。痢疾志贺菌和弗氏柠檬酸杆菌的半数致死剂量（LD）值分别为 4.50×10 菌落形成单位（CFU）/g 和 3.20×10 CFU/g。攻毒后患病中华鲟的临床症状与自然感染的中华鲟相同。组织病理学检查显示，痢疾志贺菌和弗氏柠檬酸杆菌感染的中华鲟内脏严重受损。这是首次报道痢疾志贺菌感染与中华鲟死亡有关。本研究结果揭示了痢疾志贺菌和弗氏柠檬酸杆菌在养殖中华鲟中的发病机制和严重致病性，为预防和治疗养殖鲟鱼痢疾志贺菌和弗氏柠檬酸杆菌感染提供了思路。
