BIOCHEMICAL AND BIOLOGICAL CHARACTERIZATION OF RUMINAL FUSOBACTERIUM-NECROPHORUM

Biochemical characteristics, biological activities, and antimicrobial susceptibilities of ruminal Fusobacterium necrophorum (eight subsp. ne crophorum and eight subsp. funduliforme) and of isolates (three of eac h subsp.) obtained from bovine hepatic abscesses were determined. F. n ecrophorum subsp. necrophorum strains had higher phosphatase and DNase activities, produced more leukotoxin, and were more pathogenic to mic e than subsp. funduliforme strains. The leukotoxin titer for culture s upernatants of ruminal subsp. necrophorum strains was approximately 15 times lower than that of hepatic subsp. necrophorum strains. Hemagglu tination activity was present in all hepatic, but only in some ruminal , strains of subsp. necrophorum. The antimicrobial sensitivity profile of the ruminal isolates was similar to that of hepatic isolates.