STAPHYLOCOCCI 



Staphylococci. To cocci dividing irregularly and usually forming 

 masses which are likened to clusters of grapes the term Staphylococcus 

 is applied. While there have been experiments which show that by 

 selecting pale portions of a yellow colony, eventually a white colony 

 could be produced, yet, as a practical consideration, it is convenient 

 to consider at least two types of Staphylococci: the Staphylococcus pyo- 

 genes aureus and the Staphylococcus pyogenes albus. 

 In culturing from the pus of an abscess or furuncle 

 we generally obtain a golden coccus, while in ma- 

 terial from the nose or mouth, the Staphylococcus 

 colonies are almost invariably white. As regards 

 the common skin coccus, this will be found to pro- 

 duce a white colony. A coccus which very slowly 

 liquefies gelatin and has been supposed to cause 

 stitch abscesses is the 6*. epidermidis 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. 

 Staphylococci show marked resistance to dessication and 

 dried pus may contain live organisms for months. Old 

 bouillon cultures of Staphylococci contain a ferment-like 

 substance, leucocidin, which disintegrates leukocytes. Such 

 cultures may also show a haemolysin and when filtered and 

 injected into animals show destructive action on cells of 

 various organs. Amyloid change may be caused in animals 

 by repeated injections of either living or dead cultures. 



The S. pyogenes citreus is considered as of very feeble 

 pathogenic power. Certain cocci whose colonies have pre- 

 sented a waxy appearance have been designated as S. 

 cereus albus and S. cereus flavus, respectively. They are of 

 very little practical importance. The Staphylococcus pyogenes JjJJJJ? ^/te e T old! 

 aureus grows readily at room temperature, but better at 37C. (Mac Neal.) 

 It coagulates milk and renders bouillon uniformly turbid. 



It grows on all media, as blood-serum, agar, potato, etc. It has been proposed to 

 distinguish it from skin Staphylococci by its power of producing acid in mannite. 

 Ordinarily the individual cocci are about IJJL 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. In the tropics 

 staphylococcal infections often show great virulence and clinically may resemble 

 streptococcal ones. Smears from such erysipelatoid lesions show diplococcal 

 morphology, often phagocytized. A pemphigoid eruption in children is often 

 staphylococcal (Pyosis). 



In infection of bone tissue the Staphylococcus is by far the most frequent cause. 



FIG. 13. Gelatine 



