3o6 Suppuration 



frozen by liquid air and then ground, or the culture masses are treated 

 by dilute acids and alkalies according to Vaughan, or the culture 

 masses are permitted to undergo autolysis in physiological salt 

 solution or in diluted serum containing amboceptor and complement 

 (see Bacteriolysis). 



Pathogenesis. — The virulent Staphylococcus aureus is 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. 



The classical test for virulence is to inject J/f q ^^- of ^ 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. Highly virulent cultures kill the 

 animal in from one to two days. 



The effects produced by different methods of inoculation are marked. 

 Thus, 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 is ill. In a few days the abscess points and 

 empties, the temperature returns to the normal and the animal 

 recovers. In exceptional cases a generalized injection occurs and 

 the rabbit dies. 



If the injection be made into the peritoneal 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. 



Intravenous injections are immediately followed by rise of tem- 

 perature, and the occurrence of multiple widespread foci of coloniza- 

 tion 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. 



When the cocci enter human beings subcutaneously, furuncles, 

 carbuncles and abscesses commonly result, according to the virulence 

 of the organism and the resisting power of the individual. Garre* 

 applied the organism in pure culture to the uninjured skin of his arm, 

 and in four days developed a large carbuncle, 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 produced 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 



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



t " Monatschrif t fur prakt. Dermatologie," 1887, rv, No. ib. 



