CLASSIFICATION OF THE STREPTOCOCCI OF HUMAN FECES'

The use of fermentative reactions in carbohydrate media for tracing the relationships of the streptococci was first suggested by Gordon in 1904 and elaborated by Houston in 1905 and by Andrewes and Horder in 1908. The last two were able, from their own results and those of Gordon, to divide the streptococci into seven sub-groups or species which they considered main types or type centers about which the more variable forms were clustered. This paper is concerned with their sixth type, Strep. fecalis, which ferments sucrose, lactose, salicin, coniferin and mannitol. In general, the problem resolved itself into the isolation and differentiation of the streptococci found in some thirty specimens of human feces. Over five hundred cultures were isolated and classified according to their fermentative reactions. The media used were prepared according to standard methods. It was found, however, that the best growth was obtainable at a pH of 7.2 to 7.4 and, furthermore, that when 1 per cent each of glucose and lactose was added to the agar plates a more vigorous growth was produced. In isolating the streptococci, a portion of a fresh stool was mixed thoroughly with sterile saline solution and one loopful smeared over three agar plates. After a forty-eight-hour growth the colonies of streptococci were located with a hand lens. In order to insure growth it was found necessary to cut the agar bordering the colony and to transfer the whole colony to a glucose sugar broth tube. Although the chance of contamination wa