[Investigations on the phylogeny of Pasteurella multocida: DNA base sequence relatedness among strains representing Carter's serogroups A through E, and elimination of biovar 6 (so-called dog-type strains) (author's transl)].

The phylogenetic relationships among strains of Pasteurella multocida representing Carter's serogroups A, B, (C), D and E, the type strain (which also represents serogroup A, and biovar 4), the indole-negative strain Schütze HS, and two "dog-type" strains (biovar 6) were investigated by DNA:DNA hybridization using the optical method. The genome DNAs of the "dog-type" strains were almost identical; they displayed, however, only 20% binding with the DNA of the type strain of P. multocida, and even lower or no measurable binding with the DNAs of the other strains tested. The taxon hitherto classified as biovar 6 of P. multocida is therefore considered as a distinct species; yet the data so far available do not rule out that it belongs to a genus other than Pasteurella sensu stricto. - The remaining strains exhibited high genome DNA relatedness, with between 64 and 98% DNA binding. The present data do not rule out the existence of molecular subspecies in P. multocida.