Classification and identification of Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus by cluster analysis and deoxyribonucleic acid hybridizations

Fifteen gram‐negative, saccharolytic rods isolated from advanced periodonlal pockeis were compared to type and reference strains of Arlinohacillus actinomycetemcomitans, Haemaphilus aphrophilus, and reference strains of Haemophilus paraphrophilus. Phenotypic features of organisms were used in cluster analysis and multidimensional scaling. Deoxyribonucleic acid (DNA) was extracted from all strains and moles percent guanine plus cytosine content determined. DNA/DNA homology experiments were performed between reference strains of each species and oral isolates. Five strains from periodontosis lesions, two strains from Papillon‐Lefevre periodontal lesions, and four strains from periodontitis pockeis of adults were similar to A. actinomycetemcomitans by cluster analyses and by DNA/DNA homologies. Except for a single H. paraphrophilus isolate, the H. aphrophilus and H, paraphrophilus isolates could not be distinguished as two distinct species as there was overlap in biochemical characteristics and DNA/DNA homology. Two strains isolated from periodontosis lesions, two strains from adult periodontilis sites, and three oral reference strains were very similar to each other and to the H. aphrtiphilus type strain using phenotypic features. Hydrogen peroxide decomposition was not found to be a consistent feature of A. actinomycetemcumitans strains isolated from periodontal pockets.