Staphylococcus Pyogenes Aureus at Albus 315 



some of the staphylococci into the circulation in animals whose 

 cardiac valves had been injured by a sound passed into the carotid 

 artery; and Ribbert has shown that the injection of cultures of the 

 organism may cause valvular lesions without preceding injury. 



Pathogenesis. — The Staphylococcus aureus is therefore a danger- 

 ous and sometimes a deadly organism. Its virulence is, however, 

 very variable both for the lower animals and for man. The most 

 susceptible laboratory animal is the rabbit. Guinea-pigs, rats, mice, 

 dogs and cats are much less susceptible. 



Intravenous Injections. — The classical test for virulence is to inject 

 J^o cc. of a twenty-four hour old bouillon culture into the ear vein 

 of a middle-sized rabbit. If of the ordinary virulence, the organism 

 should kill the rabbit in from four to eight days, during which time 

 the animal suffers from fever and wasting, and the occurrence of 

 multiple widespread foci of colonization with minute abscesses in 

 many of the organs. The heart is sometimes the seat of purulent 

 myocarditis, less frequently of septic endocarditis. The kidneys 

 show minute abscesses, with aggregations of cocci in the glomeruli 

 and in the tubules. Highly virulent cultures kill the animal in from 

 one to two days, without abscesses. 



Subcutaneous Injection. — If a few drops of a virulent culture 

 be injected beneath the skin of a rabbit, there is a local reaction, an 

 abscess forms, the temperature rises and the animal becomes ill. 

 In a few days the abscess points and empties, the temperature re- 

 turns to the normal and the animal recovers. In exceptional cases 

 a generalized injection occurs and the rabbit dies. 



Intraperitoneal Injection. — If the injection be made into the peri- 

 toneal cavity, pleural cavity or into a joint, there is primarily a 

 localized suppuration, peritonitis, pleuritis or arthritis, which is 

 usually followed in a day or two by generalized infection and death. 



Human Injection. — When the cocci enter human beings subcuta- 

 neously, furuncles, carbuncles and abscesses commonly result, ac- 

 cording to the virulence of the organism and the resisting power of 

 the individual. Garre* apphed the organism in pure culture to the 

 uninjured skin of his arm, and in four days developed a large car- 

 buncle, with a surrounding zone of furuncles. Bockhartf suspended 

 a small portion of an agar-agar culture in salt solution, and scratched 

 it gently into the deeper layer of the skin with his finger-nail; a 

 furuncle developed. Bumm injected the coccus suspended in salt 

 solution beneath his skin and that of several other persons, and pro- 

 duced an abscess in every case. When conditions of invasion are 

 most favorable, fatal generalization of the organisms may occur. 

 In such cases they may be cultivated from the streaming blood, 

 though the greater number collect in, and frequently obstruct, the 

 capillaries. In the lungs and spleen, and still more frequently in 



* "Fortschritte der Med.," 1885, No. 6, p. 170. 



t " Monatschrif t fiir prakt. Dermatologie," 1887, rv. No. 10. 



