Characterization and identification of bovine and ovine Pasteurellaceae isolated from the oral cavity and rumen of apparently normal cattle and sheep.

Reinvestigations of 121 strains previously described as Actinobacillus lignieresii showed that only fifteen strains (12%) had phenotypic characters compatible with A. lignieresii sensu stricto. Four strains were diagnosed as Pasteurella multocida and nine strains as P. haemolytica biogroup 1. The remaining organisms had phenotypic characters compatible with Pasteurellaceae, but could not be classified with accepted species. Fifty-one of the strains investigated had phenotypic characters allowing classification with P. haemolytica biogroups 6 through 9. In addition 19 strains made up at least two new biogroups within the bovine and ovine P. haemolytica complex. Twenty-seven unclassified ovine isolates formed a heterogeneous group provisionally designated taxon 18. At least four biovars were demonstrated within taxon 18. The taxonomic significance of characters separating the P. haemolytica complex and taxon 18 as well as characters separating biogroups within these groups remains to be investigated genetically. The necessity of extended phenotypic characterization within the family Pasteurellaceae Pohl 1981 is underlined by the present findings.