Characterization of Actinobacillus strains isolated from aborted swine fetuses

Eleven Actinobacillus strains were isolated in pure culture from 12- to 13-week-old aborted swine fetuses. Apart from minor biochemical differences, they resembled strains isolated from sow vaginas by Ross et al. (1972) in the U. S. A. Some of the strains agglutinated sheep, cattle and horse but not pig, dog and chicken erythrocytes. Haemagglutination was mannose resistant and could be inhibited by specific hyperimmune serum. Heating above 70 degrees C diminished or abolished haemagglutination of the cultures. Electron microscopy showed no fimbriae on the surface of the bacteria.