ACIDURIC BACTERIA 385 



The method of complement fixation, precipitin test, ophthalmo reac- 

 tion and intracutaneous reaction with various preparations of B. 

 abortus have been tested for their diagnostic value, but the results 

 are not clear cut and definite. 1 



Prophylaxis and Dissemination. The infection of market milk with 

 B. abortus focuses attention sharply upon the transmissibility of the 

 organism to man. Definite details are lacking, but pasteurization of 

 milk should remove all practical danger from this source. 



ACIDURIC BACTERIA. 2 



There is a somewhat poorly defined group of bacilli, chiefly found 

 in the intestinal contents of man and animals, 3 which possesses the 

 unusual property of growing in fermentation media of a degree of 

 acidity incompatible with the development of all other known bacteria. 

 The aciduric bacteria are of two kinds: the true aciduric bacilli, of 

 which Bacillus acidophilus is the best known, and facultatively 

 aciduric bacteria, 4 which are occasionally detected in the intestinal 

 contents of man and animals fed for some time upon carbohydrate. 

 The facultative organisms rapidly lose their acid tolerance upon cul- 

 tivation in ordinary media, and they are probably to be regarded as 

 examples of bacterial adaptation. 



Rahe 5 distinguishes three types of aciduric bacilli, depending upon 

 their action upon carbohydrates. Acid, but no gas is formed, as 

 follows : 



Type I. Bacillus bulgaricus (not an intestinal organism) coagulates 

 milk, but does not ferment mannite. 



Type II. Coagulates milk and ferments mannite. 



Type III. Does not coagulate milk, but ferments mannite. 



Bacillus Acidophilus. Bacillus acidophilus, described by Moro 6 

 and independently by Finkelstein 7 is a somewhat pleiomorphic bacillus 

 of varying length, which occurs singly or in pairs as a rule. Chain 

 formation is not uncommonly observed in cultures on artificial media. 

 The organism forms no spores or capsules and it is typically Gram- 



1 See Klimmer, Ergebnisse der Immunitatsforsoh. u. experimentelle Therap., 1914, i, 

 143-188, for details. 



2 Kendall, Jour. Med. Research, 1910, xxii, 153 for resume and literature to 1910. 

 See also Rahe, Jour. Inf. Dis., 1914, xv, 141. 



3 Mereschkowsky, Centralbl. f. Bakt., Orig., 1905, xxxix, 380, 584, 696; 1906, xl, 118. 

 < Kendall, loc. cit., p. 165. 



5 Loc. cit. 



e Wien. klin. Wchnschr., 1900, v, 114. 

 7 Deutsch. med. Wchnschr., 1900, xxii, 263. 

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