Laboratory of Fish Diseases, National Institute of Oceanography and Fisheries, Alexandria, Egypt.
Department of Fish Diseases and Management, Faculty of Veterinary Medicine, Suez Canal University, Egypt.
Microb Pathog. 2018 Aug;121:1-8. doi: 10.1016/j.micpath.2018.04.021. Epub 2018 Apr 16.
The present study was investigating the clinical pictures, prevalence, as well as the ecological conditions associated with Pseudomonas anguilliseptica outbreaks in four cultured seabream, Sparus aurata farms at different localities in Egypt during winter of 2016. The phenotypic and genotypic patterns of Pseudomonas isolates were investigated. The existence of intraspecific heterogeneity among different isolates was analyzed using Restriction Fragment Length Polymorphism (RFLP) technique. Attempts on disease control using antibiogram or dietary supplement were also considered. To achieve these goals, various commercial antibiotic discs were analyzed against Ps. anguilliseptica isolates using the disc diffusion method. Additionally, the impact of one-month dietary incorporation with 3% garlic extract or 0.5% potassium diformate on S. aurata viability and response for prolonged bathing treatment with florfenicol was evaluated following challenge with the virulent strain of Ps. anguilliseptica. Most of the naturally infected fish displayed spiral-swimming behavior with no obvious external lesions. The prevalence of infections in the four investigated farms (F1, F2, F3, and F4) were 44.9, 69.04, 67.72, and 83.4%, respectively. Water analysis revealed a significant variation in total hardness, pH, dissolved oxygen (D.O), ammonia and salinity among different localities. All isolates were rather uniform in most of the biochemical characteristics and were identical on the basis of RFLP analysis. The analyses of PAF-PAR gene pointed out specific amplification bands of 439 bp length. The antibiogram revealed a potential activity of florfenicol, ciprofloxacin, nitrofurantoin, and oxytetracycline against all isolates. Experimentally challenged fish fed on garlic extract or potassium diformate presented lower mortality and better therapeutic response to florfenicol than those fed on a normal basal diet. In conclusion, Ps. anguilliseptica is a prevalent pathogen among cultured seabream where dietary inclusion of 3% garlic extract or 0.5% potassium diformate seemed to improve seabream health status and subsequently, increase the efficacy of the treatment with the selective antibiotic.
本研究调查了 2016 年冬季埃及四个不同地点养殖真鲷 Sparus aurata 养殖场中，与假单胞菌 anguilliseptica 暴发相关的临床症状、流行率和生态条件。研究了假单胞菌分离株的表型和基因型模式。使用限制性片段长度多态性（RFLP）技术分析了不同分离株之间的种内异质性。还考虑了使用抗生素图谱或饮食补充来控制疾病。为了实现这些目标，使用圆盘扩散法分析了各种商业抗生素对 Ps. anguilliseptica 分离株的作用。此外，评估了在受到毒力菌株感染后，用氟苯尼考进行长时间沐浴处理之前，在一个月的饮食中添加 3%大蒜提取物或 0.5%二羟甲酸钾对真鲷活力和反应的影响。大多数自然感染的鱼表现出螺旋游动的行为，没有明显的外部病变。在四个调查农场（F1、F2、F3 和 F4）中，感染的流行率分别为 44.9%、69.04%、67.72%和 83.4%。水质分析显示，不同地点的总硬度、pH 值、溶解氧（D.O）、氨和盐度存在显著差异。所有分离株在大多数生化特性上都相当一致，并且根据 RFLP 分析结果相同。PAF-PAR 基因分析显示出 439bp 长度的特定扩增带。抗生素图谱显示，氟苯尼考、环丙沙星、呋喃妥因和土霉素对所有分离株均具有潜在活性。与正常基础饮食相比，用大蒜提取物或二羟甲酸钾喂养的实验性感染鱼的死亡率较低，对氟苯尼考的治疗反应更好。总之，假单胞菌 anguilliseptica 是养殖真鲷中的一种流行病原体，在饮食中添加 3%大蒜提取物或 0.5%二羟甲酸钾似乎可以改善真鲷的健康状况，从而提高选择性抗生素的治疗效果。
