Corynebacterium pseudotuberculosis: biochemical properties, production of toxin and virulence of ovine and caprine strains.

Twenty-two strains of Corynebacterium pseudotuberculosis, the causative agent of caseous lymphadenitis, were isolated from typical abscesses in sheep and goats from flocks in 6 different regions of France and were characterized. These strains were uniform in biochemical characteristics, susceptibility to 8 antimicrobial agents, and virulence for OF1 mice. All these strains produced an exotoxin, identified by inhibition of staphylococcal beta-hemolysin. Moreover, this study showed that strain 19R, a streptomycin-resistant mutant used in experimental infection in sheep, possessed the same characteristics as the field strains of C. pseudotuberculosis, except for its resistance to streptomycin (500 micrograms/ml).