Avendaño-Herrera R, Irgang R, Sandoval C, Moreno-Lira P, Houel A, Duchaud E, Poblete-Morales M, Nicolas P, Ilardi P
Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas, Universidad Andrés Bello, Viña del Mar, Chile.
Interdisciplinary Center for Aquaculture Research (INCAR), Concepción, Chile.
Transbound Emerg Dis. 2016 Apr;63(2):121-6. doi: 10.1111/tbed.12464. Epub 2016 Jan 8.
In this study, we isolated, identified and characterized isolates of Tenacibaculum dicentrarchi in Atlantic salmon (Salmo salar) farmed in Chile for the first time. In 2010 and 2014, mortalities were observed in Atlantic salmon (average weight 25-30 and 480-520 g, respectively) at an aquaculture centre in Puerto Montt, Chile. Severe tail rots, frayed fins and, in some cases, damaged gills were detected. Wet smear analyses of these lesions revealed a high occurrence of Gram-negative, filamentous bacteria. Microbiological analysis of infected gill and tail tissues yielded six bacterial isolates. All were identified as T. dicentrarchi through polyphasic taxonomy, which included phenotypic characterization, 16S rRNA sequencing and multilocus sequence typing. The latter method revealed a close relationship of the Chilean genotype with the T. dicentrarchi type strain and two Norwegian Atlantic cod (Gadus morhua) isolates. The pathogenic potential of the TdChD05 isolate was assessed by challenging Atlantic salmon and rainbow trout (Oncorhynchus mykiss) for one hour, which resulted in mean cumulative mortality rates of 65% and 93%, respectively, as well as clinical signs 14 days post-challenge. However, challenged Coho salmon (Oncorhynchus kisutch) presented no mortalities or clinical signs of infection. These findings indicate that the geographical and host distribution of T. dicentrarchi is wider than previously established and that this bacterium may have negative impacts on salmonid cultures.
在本研究中，我们首次对智利养殖的大西洋鲑（Salmo salar）中的双棘黄杆菌分离株进行了分离、鉴定和特征描述。2010年和2014年，在智利蒙特港的一个水产养殖中心观察到了大西洋鲑（平均体重分别为25 - 30克和480 - 520克）的死亡情况。检测到严重的尾部腐烂、鳍条磨损，在某些情况下还发现鳃受损。对这些病变进行的湿涂片分析显示革兰氏阴性丝状细菌的高发生率。对受感染的鳃和尾部组织进行微生物学分析，得到了6株细菌分离株。通过多相分类法将所有分离株鉴定为双棘黄杆菌，该方法包括表型特征分析、16S rRNA测序和多位点序列分型。后一种方法揭示了智利基因型与双棘黄杆菌模式菌株以及两株挪威大西洋鳕（Gadus morhua）分离株之间的密切关系。通过对大西洋鲑和虹鳟（Oncorhynchus mykiss）进行一小时的攻毒试验，评估了TdChD05分离株的致病潜力，结果在攻毒后14天分别导致平均累积死亡率为65%和93%，以及出现临床症状。然而，攻毒的银大麻哈鱼（Oncorhynchus kisutch）未出现死亡或感染的临床症状。这些发现表明，双棘黄杆菌的地理分布和宿主范围比以前确定的更广，并且这种细菌可能对鲑科养殖产生负面影响。
