CHAPTER XXI 



STAPHYLOCOCCIC INFECTION 



The Organism. In his study of wound infection, Ogston recog- 

 nized two groups of bacteria with different morphologic characteristics. 

 In one the cocci are arranged in chains, in the other they are in bunches. 

 The former he designated as streptococci and the latter as staphylo- 

 cocci. Of the staphylococci one group is chromogenic and the other 

 is not. The former is known as Staphylo coccus pyogenes aureus, and 

 the latter as albus. The staphylococci constitute a large group with 

 many varieties, differing more or less widely in cultural, tinctorial and 

 pathogenic properties. 



The individual cocci are quite variable in size, which seems to be 

 influenced by food, age and temperature. They take the basic anilin 

 stains easily, also certain acid stains, and are slightly colored by hemo- 

 toxylin. The readiness with which such a variety of stains may be 

 employed has favored attempts to ascertain the finer structures of 

 these organisms. Some are convinced that the cocci consist of a distinct 

 membrane with protoplasmic content, while others find evidence of 

 well-defined nuclei. However, all of this work needs more extended 

 study before the conclusions reached by different observers can be 

 correlated and accepted. 



The optimum growth temperature is that of the animal body, 

 though multiplication continues at temperatures as high as 43 C. and 

 as low as 10 C. Free oxygen is not essential and growth will proceed 

 in proper media in an atmosphere of hydrogen, but not in carbonic 

 acid, nitrogen or illuminating gas. It does not grow abundantly in 

 media containing no protein, but it may obtain its nitrogen from 

 ammonia salts, kreatin or asparagin. It develops abundantly in pep- 

 tone solutions, but this is not an essential constituent of nutritive 

 media. A feebly alkaline reaction is most favorable, but feeble 

 acid does not prevent growth. In bouillon at incubator temperature 

 multiplication proceeds with great rapidity ; one loop of such a culture 



