NOT DESCRIBED IN SECTIONS IV. AND V. 321 



31. STREPTOCOCCUS OF MASTITIS IN COWS. 



Obtained by Nocard and Mollereau (1887) from the milk of cows suffering 

 from a form of chronic mastitis (mammite contagieuse). 



Morphology. Spherical or oval cocci, a little less than one // in diameter, 

 usually united in long chains. 



Stains with the usual aniline colors and also by Gram's method. 



Biological Characters. An aerobic and facultative anaerobic, non- 

 liquefying streptococcus. Grows in the usual culture media at the room 

 temperature. Develops rapidly in milk or in bouillon at a temperature of 

 16 to 30 C. The milk of a cow suffering from the form of mastitis produced 

 by this micrococcus, when drawn with proper precautions in sterilized test 

 tubes, at the end of twenty-four hours is acid in reaction; the lower two- 

 thirds of the tube is filled with an opaque, dirty- white, homogeneous deposit, 

 and above this is an opalescent, serous fluid of a bluish or dirty-yellow or 

 slightly reddish color, according to the age of the lesion. A drop of this 

 milk examined under the microscope shows the presence of the streptococcus 

 in great numbers. The addition of two to five per cent of glucose or of gly- 



FIQ. 99. Streptococcus of mastitis in cows (Nocard). 



cerin to bouillon makes it a more favorable culture medium ; the reaction 

 should be neutral or slightly alkaline, as this streptococcus does not grow 

 readily in an acid medium, although it produces an acid reaction in media 

 containing sugar, the acid formed being lactic. In gelatin stick cultures the 

 growth upon the surface is scanty, in the form of a thin pellicle around the 

 point of puncture ; along the line of inoculation minute, opaque, granular 

 colonies are developed, which, being closely crowded, form a thick line with 

 jagged mai'gins. 



In agar stick cultures the growth is similar but more abundant. Upon 

 the surface of nutrient gelatin, agar, or blood serum a large number of mi- 

 nute, spherical, semi-transparent colonies are developed along the impfstrich ; 

 these have a bluish tint by reflected light ; they may become confluent, form- 

 ing a thin layer with well-defined margins. Upon gelatin plates, at 16 to 

 18 C., colonies are first visible at the end of two or three days ; they are 

 spherical and slightly granular, at first transparent and later of a pale-yellow 

 color by transmitted light, which gradually becomes brown. At the end of 

 five or six weeks the colonies are still quite small, well defined, and opaque. 



Pathogenesis. Pure cultures injected into the mammary gland of cows 

 and goats gave rise to a mastitis resembling in its development that from 

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