154 BACTERIA 



growth develops. In bouillon there is a marked even cloudiness, 

 with a fine pellicle on surface; moderate sediment, which upon 

 shaking is broken up. Milk is rendered acid and curdles very 

 soon, the curd being digested finally. 



Potato cultures are dry, whitish then yellow, and finally deep 

 orange. 



Habitat. Widely distributed; found in dirty water, sewage, air, 

 dust of streets and houses; also upon the skin; normally present in 

 the mouth, nose, rectum, anterior urethra, vagina, and external ears. 



Pathogenesis. In man it is the cause of carbuncles, abscesses, 

 osteomyelitis, septicaemia, puerperal infection, and any inflamma- 

 tion of the serous membranes. It causes acne and boils; can, and 

 does attack any tissue of the body. Endocarditis is a very grave 

 affection that is caused by this organism. It also plays an 

 important role in secondary infection, causing necrosis of pre- 

 viously infected tissues (tubercles) and is active in small-pox and 

 diphtheria. Experimental endocarditis has been produced in 

 animals by injecting it into the veins. By passage through 

 animals it is rendered highly virulent. In young, diabetic and 

 anaemic subjects, its action is often rapidly fatal. Its pathogenic 

 action is often wide and disastrous. By growing it under an ae- 

 robic conditions its virulence may be intensified, and the ac- 

 tivity with which it liquefies gelatine is an index of its malignancy. 



In man acne, boils, and carbuncles have followed the rubbing of 

 culture into the skin. 



Immunity. Careful injections may result in the immunization 

 of the lower animals. An anti-serum with opsonic, agglutinative, 

 lytic and anti-toxic properties has been produced and, if used 

 fresh, seems to have a slight beneficial effect upon staphylococcus 

 septicemia. Too little is known for definite statements. Bac- 

 terins made from this germ have been used with excellent results 

 in all but the very aggravated and fulminating affections caused 

 by it. Bacterin treatment of acne and furunculosis has estab- 

 lished itself as most efficacious. 



