Haghighi Karsidani S, Soltani M, Nikbakhat-Brojeni G, Ghasemi M, Skall Hf
Department of Aquatic Animal Health, Faculty of Veterinary Medicine, University of Tehran.
Iran J Microbiol. 2010 Dec;2(4):198-209.
Streptococcosis/lactococcosis is a hyperacute systemic disease that can occur in marine and fresh waters of many species of fish. The aim of this work was to study the disease outbreak in the major rainbow trout (Oncorhynchus mykiss) production of Iran.
108 Gram positive cocci isolates were obtained from diseased trout in seven provinces with major trout production during 2008 till 2009. These bacterial isolates were characterized using phenotypic and molecular studies. The isolates were also analysed phylogeneticaly and compared with the available data.
49 samples (45.37%) were identified as Streptococcus iniae, 37 samples (35.2%) matched with Lactococcus garvieae; and 22 samples (19.43%) were identified as members of Streptooccus genus by culture-based and biochemical tests of API 50 CH, API 20 STREP and rapid 32 STREP systems. Using universal primers for differentiation of Streptococcus sp. and Enterococcus sp, all 108 samples were identified as Streptococcus sp. with a target region of 500 bp. Single specific PCR resulted in identification of 64 (59.2%) isolates as S. iniae and 44 (40.8%) isolates as L. garvieae. The phylogenetic analysis of the S. iniae isolates resulted in maximal similarity to some strains reported from Taiwan and to all Brazilian strains. Also, one strain showed less sequence similarity values with other tested strains although this strain has high similarity with ATCC 29178 strain, all reported Chinese, and some Taiwanian strains. Also, analysis of S. iniae LctO gene sequence showed that this isolate clustered within the S. iniae group. The sequence analysis of L. garvieae strains also showed that they have maximum similarity to all Japanese and Chinese strains, but one strain has lower sequence similarity values with all other recorded strains.
[corrected] The results of this study clearly show that trout farming in Iran is severely affected by both species of S. Iniae and L. garvieae and requires serious preventive criteria.
链球菌病/乳球菌病是一种超急性全身性疾病，可在多种鱼类的海水和淡水中发生。本研究的目的是调查伊朗主要虹鳟（Oncorhynchus mykiss）养殖中该病的爆发情况。
2008年至2009年期间，从七个主要养殖鳟鱼省份的患病鳟鱼中获取了108株革兰氏阳性球菌分离株。通过表型和分子研究对这些细菌分离株进行了鉴定。还对分离株进行了系统发育分析，并与现有数据进行了比较。
通过基于培养的API 50 CH、API 20 STREP和快速32 STREP系统的生化试验，49个样本（45.37%）被鉴定为海豚链球菌，37个样本（35.2%）与格氏乳球菌匹配；22个样本（19.43%）被鉴定为链球菌属成员。使用用于区分链球菌属和肠球菌属的通用引物，所有108个样本均被鉴定为链球菌属，目标区域为500 bp。单特异性PCR鉴定出64株（59.2%）分离株为海豚链球菌，44株（40.8%）分离株为格氏乳球菌。海豚链球菌分离株的系统发育分析结果显示与台湾报道的一些菌株以及所有巴西菌株具有最大相似性。此外，一株菌株与其他测试菌株的序列相似性值较低，尽管该菌株与ATCC 29178菌株、所有报道的中国菌株以及一些台湾菌株具有高度相似性。此外，对海豚链球菌LctO基因序列的分析表明，该分离株聚集在海豚链球菌组内。格氏乳球菌菌株的序列分析也表明，它们与所有日本和中国菌株具有最大相似性，但一株菌株与所有其他记录菌株的序列相似性值较低。
本研究结果清楚地表明，伊朗的鳟鱼养殖受到海豚链球菌和格氏乳球菌这两种细菌的严重影响，需要采取严格的预防措施。
