Numerical Taxonomy of Haemophilus and Related Bacteria

Abstract

A numerical taxonomic study of named strains of Haemophilus Winslow et al., Actinobacillus Brumpt, and Pasteurella Trevisan was made using 134 characters covering a wide range of properties. The strains fell into four main clusters. Three of these represented Haemophilus. Cluster 1 contained strains requiring X factor and usually also V factor and corresponded to H. influenzae (Lehmann and Neumann) Winslow et al. and closely allied organisms. Cluster 2 contained strains that required only V factor and corresponded to H. parainfluenza Rivers and similar organisms. Cluster 3 contained strains with a requirement for a raised CO2 tension and contained H. aphrophilus Khairat and H. paraphrophilus Zinnemann. Cluster 4 contained strains of Actinobacillus and Pasteurella but not Yersinia van Loghem. The three genera Actinobacillus, Pasteurella, and Haemophilus have a close phenetic relationship and are facultative anaerobes that can acidify glucose fermentatively. They might best be separated from the other genera of the family Brucellaceae Breed et al.