Streptococci isolated from bovine intramammary infections.

Streptococcal isolates from 71 dairy herds considered free of Streptococcus agalactiae were compared with isolates from 1 herd used in bovine mastitis research over a 12-year period. The incidence of streptococci was as follows: Streptococcus uberis, 56.5%; enterococci, 24.2%; Streptococcus dysgalactiae, 9.0%; Streptococcus bovis, 5.1%; unclassified streptococci, 3.1%; Streptococcus agalactiae, 1.5%; and Lancefield group G streptococci, 0.7%. The incidence for these streptococci in the 2 groups was generally the same except for Str bovis and unclassified streptococci. A study of cultural responses in numerous mediums indicated that differentiation of streptococci recovered from the bovine udder may be obtained with esculin broth, CAMP test, sodium hippurate broth, 0.1% methylene blue milk, inulin, and raffinose broths.