Abstract
A series of strains of hemolytic streptococci and mucoid encapsulated streptococci was obtained from the throats of scarlet fever patients at Cook County Contagious Hospital.
Laboratory studies were made on a group of these strains to determine. (1) the results of their growth on chocolate agar, (2) their effect on the sugars sorbitol and trehalose and (3) the influence of mouse passage on capsule formation and colony characteristics.
Using chocolate agar Tunnicliff 1 found that hemolytic streptococci of scarlet fever produced no color change in this medium except occasionally a slight greening after several days'growth. The colonies almost always were conical in shape and slightly granular. Occasionally, however, a strain dissociated and produced atypical colonies that were large, moist, smooth and convex and turned chocolate agar green. These atypical colonies were not scarlatinal by the opsonic, agglutination or toxin neutralization tests. 2 , 3
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