STAPHYLOCOCCI. 



45 



pyogenes aureus and the staphylococcus pyogenes albus. In culturing 

 from the pus of an abscess or furuncle we generally obtain a golden 

 coccus, while in material from the nose or mouth, the staphylococcus 

 colonies are almost invariably white. As regards the common skin 

 coccvs, this will be found to produce a white colony. A coccus which 

 very slowly liquefies gelatin and has been sup- 

 posed to cause stitch abscesses is the S. epi- 

 dermidis albus. 



While it is customary to look for a golden 

 colony in the case of organisms showing 

 virulence, yet at times a cream -white colony 

 may develop from cocci of great virulence. 



The S. pyogenes citreus is considered as of 

 very feeble pathogenic power. Certain cocci 

 whose colonies have presented a waxy appear- 

 ance have been designated as S. cereus albus 

 and S. cereus flavus, respectively. They are of 

 very little practical importance. The staphylo- 

 coccus pyogenes aureus grows readily at room 

 temperature, but better at 37 C. It coagulates 

 milk and renders bouillon un'formly turbid. 

 It grows on all media, as blood-serum, agar, 

 potato, etc. It has been proposed to distin- 

 guish it from skin staphylococci by its power 

 of producing acid in mannite. Ordinarily 

 the individual cocci are about la in diameter, 

 but they vary greatly in size according to the 

 age of the culture and other conditions. The 

 aureus, as it is frequently called, is not only 

 often found in circumscribed processes, but it 

 is a frequent cause of septicaemia, osteomyelitis, endocarditis, etc. It is 

 the organism most frequently concerned in terminal infections. The 

 lowered resistance of the patient permits of their passage through bar- 

 riers ordinarily resistent. Not only should this be kept in mind when 

 such organisms are isolated at an autopsy, but as well the fact that their 

 entrance may have been agonal or subsequent to death. 



FIG. 12. Gelatine cul- 

 ture Staphylococcus 

 aureus one week old. 

 (Williams.) 



