Risk assessments of the emerging fish pathogen in the environmental condition of rising water temperature.

TH-CR（托德-休伊特刚果红）琼脂用于检测和推定从人工或自然感染的鱼中获得的GCSD（C群无乳链球菌）。人工感染的鱼在较高温度（28°C）下观察到典型症状，因此需要在高水温季节注意。遗传分析表明，分离的鱼在遗传上非常相似，DNA含量高。DNA亲缘性和序列同源性。在GCSD收集的亚洲国家中，除台湾收集的菌株和中国收集的PP1564菌株外，有17株菌株对土霉素耐药并携带tet(M)基因。不同鱼类分离菌株的氨基酸序列相同。设计了一套soffd基因引物，并应用于鱼类与哺乳动物分离物的PCR检测。

TH-CR(Todd-Hewitt Congo red) agar was developed to detect and presumptively identify the GCSD(Group C Streptococcus dysgalactiae) obtained from artificially or naturally infected fish. Typical symptoms were observed in artificially infected fish at higher temperature(28°C), thus need an attention at the high water temperature season. The genetic analysis revealed that the fish isolates were genetically very similar to each other with high DNA. DNA relatedness and sequence homology. Seventeen isolates in GCSD collected Asian countries were found to be resistant to oxytetracycline and carried the tet(M) gene, except for the strains collected in Taiwan and the PP1564 strain collected in China. The amino acid sequence of SOF was identical among fish isolates. A primer set targeting the sof-FD gene was designed and applied to a PCR assay for discriminating fish isolates from mammalian isolates.