204 VETERINARY BACTERIOLOGY 



infections in veterinary practice cannot be determined at present 

 from the data available. It is possible that in some diseases, 

 particularly of equines, a serum, either curative or prophylactic, 

 prepared from a homologous organism, may prove practicable 

 and helpful. 



Diagnosis. Smears of pus stained with methylene-blue or 

 by Gram's method will usually reveal the organism if present 

 in any numbers. Sometimes the pus seems to be practically 

 sterile upon microscopic examination, but cultures prepared from 

 it will reveal the presence of the Streptococcus. 



Transmission and Prophylaxis. The constant presence of 

 various strains of this organism upon the hair and skin makes the 

 prevention of its entrance into wounds difficult. Cleanliness 

 and the use of mild antiseptics are the only practicable methods 

 of inhibiting its growth. In those infections which are character- 

 ized by a specialized organism, and which are more or less con- 

 tagious, isolation of infected animals and quarantine of those 

 exposed, with disinfection of barns, particularly stalls and mangers, 

 are the methods which must be used in checking the spread. 



Streptococcus lacticus 



Synonyms. Bacillus lactici acidi. 



Strangely enough, the organisms first isolated from milk, and 

 described as the cause of its souring, are not the ones now re- 

 garded as most commonly associated with this change. These 

 were members of the intestinal group, or bacilli that produce both 

 acid and gas in milk. Leishman, in 1899, gave the name Bacillus 

 lactici acidi to an organism which he isolated from soured milk, 

 and regarded as the common cause of this fermentation. Kruse 

 later showed that Leishman had been mistaken in regarding it 

 as a bacillus, and renamed the organism Streptococcus lacticus. 

 Since then experimental data have accumulated, which seem to 

 demonstrate quite conclusively that normal souring of milk is 

 brought about in the vast majority of cases by this organism. 

 The work of Heinemann in this country served materially to clear 

 up the relationship between this and other forms. 



Distribution. Streptococcus lacticus is found generally in milk, 

 butter, and cheese, upon the skin and hair of cattle, and in feces. 



