Deoxyribonnucleic Acid Relatedness Among Strains of Actinobacillus spp. and Pasteurella ureae

Forty strains of Actinobacillus lignieresii, Actinobacillus equuli, Actinobacillus suis, Actinobacillus capsulatus, and Pasteurella ureae were 30 to 100% related as determined by deoxyribonucleic acid (DNA)-DNA hybridization (S1 nuclease method) and could be subdivided into five DNA hybridization groups. The DNA relatedness among A. suis, A. equuli, and P. ureae strains is indicative of some overlap among these three species. A comparison of DNA relatedness data with phenetic data showed that no single test can definitely separate A. suis from A. equuli. “Actinobacillus salpingitidis,” the Actinobacillus sp. described by Ross et al. (Int. J. Syst. Bacteriol. 22:39–46, 1972), “Actinobacillus seminis,” Actinobacillus actinomycetehicomitans, Pasteurella multocida, Pasteurella haemolytica, Pasteurella aerogenes, Pasteurella gallinarum, Pasteurella pneumotropica, “Pasteurella betti”, “Pasteurella anatipestifer,” and Pasteurella testudin is were only 0 to 11% related to P. ureae, A. suis, A. equuli, A. capsulatus, and A. lignieresii.