中国水产科学Issue(6)：1244-1252,9.DOI:10.3724/SP.J.1118.2014.01244
齐口裂腹鱼无乳链球菌的分离鉴定及其感染的病理损伤
Isolation, identification and pathogenicity of Streptococcus agalactiae from Schizothorax prenanti
余泽辉 1张佳 1耿毅 1邓梦玲 1汪开毓 1黄小丽 1陈德芳 1王均1
作者信息
- 1. 四川农业大学 动物医学院，四川 雅安 625014
- 折叠
摘要
Abstract
In 2012-2013, a serious infectious disease characterized by exophthalmia, hemorrhage, and neurological symptoms emerged in Schizothorax prenanti farms in Sichuan Province. A Gram-positive, chain-forming coccus was found in liver and kidney smears. Two strains of Gram-positive, chain-forming cocci were isolated from the diseased fish. The colonies had a smooth-surface and were white, circular, regular and pin-head sized after incubation at 28℃for 48 h on brain heart infusion (BHI). Artificial infection proved that the isolates were the pathogen of the disease. It was primarily identified to be Streptococcus agalactiae according to morphological, physiological and biochemical characteristics. Furthermore, a 16S rRNA gene sequence analysis by BLAST in GenBank indicated that the two isolates showed high levels of similarity to S. agalactiae (more than 96.5%). A phylogenetic tree was constructed comparing the 16S rDNA sequences of both isolates (GenBank accession number KF773744 and KF761304) to other related bacterial species in the GenBank database. In the phylogenetic tree the two isolates and other S. agalactiae strains constituted a branch. In addition, the two isolates were positive in a specific PCR detection of S. agalactiae based on the cfb gene. Based on the phenotypic characteristics, phylogenetic analysis of the 16S rRNA gene, and specific PCR detection, both isolates were identified as S. agalactiae. The sensitivity results showed that both strains were sensitive to doxycycline, amoxicillin, cephalothin V, ofloxacin and levofloxacin, but showed some difference in sensitivity to neomycin and amikacin. Histopathologically, the S. agalactiae infection could cause serious pathological changes in multi-organs and tissues, especially in liver, kidney and brain. The main pathologic lesions were degeneration, necrosis and infiltration of the inflammation cells. Electron microscopical examination found that bacteria could invade hepatocytes, renal cells and neurons, causing destruction of mitochondria and endoplasmic reticulum.关键词
齐口裂腹鱼/无乳链球菌/16S rDNA/cfb基因/病理损伤Key words
Schizothorax prenanti/Streptococcus agalactiae/16S rDNA/cfb gene/pathological lesion分类
农业科技引用本文复制引用
余泽辉,张佳,耿毅,邓梦玲,汪开毓,黄小丽,陈德芳,王均..齐口裂腹鱼无乳链球菌的分离鉴定及其感染的病理损伤[J].中国水产科学,2014,(6):1244-1252,9.
