Abstract
Direct fluorescent antibody technique (FAT) was evaluated as a differentiation method between α-hemolytic Streptococcus sp. (KUSUDA et al., 1976; KUSUDA et al., 1978) and β-hemolytic Streptococcus sp. (MINAMI et al., 1979; KITAO et al., 1981; OHNISHI and Jo, 1981; UGAJIN, 1981; NAKATSUGAWA, 1983) in this report. The staining titer of fluorescent antibodies were examined by using heat-fixed smears of α-and β-hemolytic Streptococcus sp., S. iniae, S. equisimilis and fish pathogens other than Streptococcus. The fluorescent antibody against α-hemolytic Streptococcus sp. had a titer of 1: 10, 000 and reacted only to α-hemolytic Streptococcus sp. The fluorescent antibody against β-hemolytic Streptococcus sp. had a titer of 1: 1, 000 and reacted only to β-hemolytic Streptococcus sp. and S. iniae. The data presented here suggest that direct FAT can be utilized for differentiation of α- and β-hemolytic Streptococcus spp., and that β-hemolytic Streptococcus sp. has a common antigen with S. iniae.
