Abstract
Seven strains of bacteria, isolated from two piglets and two cows suffering from dermatitis or arthritis and presumed to belong to the genus Staphylococcus, were comparatively examined by the quantitative fluorometric DNA-DNA hybridization method in microplates, conventional biochemical tests and a commercial identification kit microbe (API STAPH). The DNA-DNA hybridization method is a genetic microbe identification method. In this experiment, the intensity of DNA-DNA hybridization between DNA from a test isolate and DNA from each of 26 reference species of the genus Staphylococcus which were fixed in microdilution wells was measured fluorometrically. The isolate was identified as a species which showed the strongest hybridization. All of the seven strains were identified definitely as S. hyicus by the quantitative fluorometric DNA-DNA hybridization method. In contrast, conventional biochemical tests identified three out of the seven strains as S. hyicus, but could not allow determination of species classification of the remaining four. While also, five of the seven strains assigned were identified as S. hyicus while the remaining two were assigned to several species other than S.hyicus following assessment with the commercial identification kit. The DNA-DNA hybridization method required only four hours to give results after picking up a colony. Thus, it was shown that the method is rapid and accurate, and therefore, useful for identification of S. hyicus, particularly for bacteria having atypical phenotypic characteristics.
