Abstract
Minett and his associates 1 included in mastitis streptococcus Group II certain streptococci which usually cause a more acute form of mastitis with less tendency to a permanent infection than Group I. In the serological study of these streptococci, Stableforth 2 found that, although grouped together on the basis of cultural and biochemical similarities, they could also be regarded as a serological group because they were directly or indirectly connected antigenically. Diernhofer 3 described the cultural characters of similar streptococci isolated by him, which he designated as Str. dysgalactiœ.
Lancefield 4 reported that certain nonhemolytic strains of streptococci were members of the serological Group C. In a personal communication she stated that these nonhemolytic strains were from cases of bovine mastitis.
In the serological study of 15 strains of alpha hemolytic mastitis streptococci of Group II (Str. dysgalactiœ), isolated here or obtained from 3 other laboratories, it was found that all 15 strains possessed an antigen which gives a group-specific precipitin-reaction with sera of Lancefield's serological Group C. Furthermore, the group-specific antibodies in Group C sera obtained from Dr. Lancefield could be removed by absorbing with the Group II mastitis strains. Antisera prepared from formalin-killed cultures of Group II streptococci were precipitated by the extracts of hemolytic strains of Group C.
In a personal communication of April 18, 1939, Dr. Wayne Plastridge informed the writer that mastitis strains originally classified by him as S. pseudo-agalactiœ belong to serological Group C and are culturally identical with cultures described by Diernhofer 3 as Str. dysgalactiœ.
The results show that strains of alpha hemolytic mastitis streptococci (Group II) either are related to or belong to Lancefield's serological Group C.
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