• Taxon 11;
  • Actinobacillus suis;
  • Actinobacillus equuli;
  • Pasteurellaceae

Evidence was obtained to indicate that equine strains of organisms previously described as Actinobacillus suis or hemolytic variants of Actinobacillus equuli might constitute a separate group of organisms provisionally designated taxon 11. Four biovars were noticed within taxon 11. Selected DNA:DNA hybridizations support the classification of the mannitol positive biovar 2 of taxon 11 distinct from porcine A. suis. The final taxonomical position of taxon 11, however, has to await more detailed genetic studies including all biovars of taxon 11. A species name has not been suggested for the same reasons. The present observations also indicate that strains identified as taxon 11 apparently constitute a part of the normal bacterial flora in the oral cavity of horses.