Differences in Intramammary Pathogenicity of Four Strains of Streptococcus Dysgalactiae.

The intramammary pathogenicity of four strains of Streptococcus dysgalactiae was measured by infusion of small numbers of bacteria (8-16 colony-forming units) into the teat sinus after milking. Significant differences in the infectivity of strains were detected.