746 MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC ANIMALS 



granular filiform growth appears which later may have a beaded appearance and 

 sometimes a brownish color. The gelatin is not liquefied. Milk is a favorable 

 medium for the growth of streptococci and a strong acidity and coagulation some- 

 times takes place. Growth on potato is said not to take place, but in some cases 

 an invisible growth seems to occur. LoefBer's blood serum is also a favorable 

 medium. Streptococci, as a rule, die out rapidly in cultures due to the accumulation 

 of their own products. In pus, blood, sputum, etc., the organism may be found 

 alive after several weeks or even months at room temperature. The thermal death- 

 point is about 54° in ten minutes. Direct sunlight kills within a few hours, and 

 they are readily killed by many disinfectants. 



Entrance of streptococci is afforded by any break in the surface of 

 the body. A local suppuration may be the result or it may be followed 

 by a general septicaemic condition. 

 ' In erysipelas some local injury is also probably necessary as a 

 starting-point. 



Following the local establishment of streptococci sufficient toxin 

 is elaborated to produce greater or less systemic disturbance. If a 

 septicaemia supervenes the poisoning becomes extreme and the organ- 

 isms are distributed throughout the body. 



Immunity following recovery from natural streptococcic infection 

 is very slight if any, and never of a permanent sort. Septicaemias 

 once established are generally fatal, and erysipelas can recur frequently. 



Bactericidal substances, opsonins, agglutinins and precipitins 

 have been demonstrated in immune serums, which, however, show 

 little therapeutic success. 



Streptococci are eliminated in the discharge of local infections 

 in sputum, etc., and are then probably more virulent. Infection by 

 contact from such sources is particularly dangerous. In anginas and 

 streptococcic infections of the respiratory tract, the epidemiology is 

 practically the same as for diphtheria and pneumonia. Similarly 

 erysipelas is to be treated as a contagious disease. 



In the prophylaxis of streptococcic diseases, greatest care must be 

 shown where chances of infection by the virulent strains are possible. 

 Isolation of erysipelas is universally practised in hospitals. Similarly 

 cases of puerperal sepsis and any local disease should be kept from 

 contact with other puerperae. Streptococcic pus from all sources 

 is' to be carefully destroyed. 



Streptococci seem to be always present on the exposed surfaces 

 of the body and are probably capable of giving trouble should any 



