[Genetic identification of 25 Legionella species by modified microdilution plate hybridization, and its evaluation...

Modified microdilution plate hybridization was used for genetic identification of 25 Legionella species. The cell wall of the isolate was broken down by glass beads. And the DNA was extracted, labeled photo-reactive biotin, and hybridized with reference DNAs immobilized in microdilution wells. Hybridized DNAs were detected by colormetric method. Each type strain of 25 Legionella species was clearly differentiated by this method. Among 103 clinical and environmental Legionella strains, 97 strains were genetically identified by this method. 60 strains were identified as the same species as by the conventional method. Concerned with ten strains that had been serologically identified as L. bozemanii, two strains isolated from the human lung were genetically identified as L. bozemanii, but the remaining environmental 8 strains were identified as L. anisa. Among the 35 strains of legionellae that had been unidentified at species level, by physiological and serological tests, 27 strains were genetically identified as L. pneumophila, 1 strains as L. feeleii, and another, as L. anisa, but 6 strains were not identified. We found that three strains among the 6 strains belong to a single species of genus Legionella other than the 25 reference species used in this study.