A total of 30 strains of Fusobacterium sp. isolated from gengival sulcus of 28 equines was studied in the period between January/1997 and April/1998. Bacterial isolation and antimicrobial resistance were determined by biochemical analyses and by the disk elution method. The species most frequently isolated was Fusobacterium nucleatum.

The following resistance rates were observed:

10 per cent for penicillin G, 87 per cent for eritromycin, and 97 per cent for sulfonamide. Theses results emphasize the need for monitoring the susceptibility patterns of this important bacterial groups frequently isolated from normal sites in equines