Multivariate chemosystematics demonstrate two groups of Actinobacillus actinomycetemcomitans strains.

Chemical analysis by us has indicated that Actinobacillus actinomycetemcomitans is not a homogeneous species. The present study used chemometric methods and a multitude of chemical characters to examine this further. Strains were characterized by cell sugar and fatty acid contents, lysis kinetics during EDTA and EDTA plus lysozyme exposure, methylene blue reduction, and API ZYM enzymatic assessment of whole cells and outer membrane vesicles/fragments. In total, 41 quantitative variables were analyzed from each of 9 strains and treated with principal component analysis and soft independent modeling of class analogy. These methods divided A. actinomycetemcomitans into 2 strain groups. One group contained ATCC 33384, ATCC 29522, FDC 2112 and FDC 2043; the other comprised ATCC 29524, ATCC 29523, FDC 2097, FDC 511 and FDC Y4. With an F-test, the groups (classes) of A. actinomycetemcomitans strains could be distinguished at 95% confidence limits. Both groups were distinct from members of the genera Haemophilus and Pasteurella (Haemophilus aphrophilus, Haemophilus paraphrophilus, Haemophilus influenzae, Pasteurella multocida and Pasteurella haemolytica).