MORPHOLOGY AND STAINING PROPERTIES 



195 



Staphylococcus pyogenes aureus (golden yellow pigment). 

 Staphylococcus pyogenes albus (white pigment). 

 Staphylococcus pyogenes citreus (lemon yellow pigment). 

 They are given in the order of their virulency, the aureus being the 

 most, the citreus the least virulent. 



FIG. 110 



FIG. Ill 



Staphylococcus pyogenes aureus. X 1000. 

 (Author's preparation.) 



Staphylococcus pyogenes albus. X 1000. 

 (Author's preparation.) 



Occurrence and Pathogenesis. Pyogenic staphylococci are found 

 everywhere in the outside world, but are most numerous on the skin 

 of man and animals. They are also frequently found in the feces. 

 They vary much in virulency, and are most virulent when they come 

 directly from a badly infected wound or a case of septicemia or 

 pyemia. Surgeons operating on pus cases may easily and frequently 

 do fatally infect themselves. The staphylococci, particularly the 

 Staphylococcus pyogenes aureus, are the cause of all varieties of 

 wound infections such as septicemia, pyemia, endocarditis, septic 

 pneumonia, puerperal fever, bone diseases, etc. 



Morphology and Staining Properties. In the hanging drop the 

 Staphylococcus pyogenes shows a completely globular or spherical 

 shape. It exhibits a lively Brownian molecular motion. It stains 

 well with the ordinary watery basic anilin dies. When not stained 

 too deeply it frequently shows a line in the middle dividing it into 

 two equal hemispheres. This line indicates the site where division 

 will occur when the organism multiplies. The organism is Gram 

 positive. The individual cocci vary from 0.7 to 0.9 of a micron in 

 diameter, and sometimes have a diameter up to 1.2 micron. The 

 Staphylococcus pyogenes albus and citreus are frequently larger than 

 the aureus, but the size depends largely upon the culture medium. 

 The cocci are generally smaller in young, rapidly growing cultures, 

 and larger in old, slowly growing ones. In cover-glass preparations 



