CHAPTER VII 

 STAPHYLOCOCCI 



Staphylococci are commonly present in air, dust and soil, frequently in the 

 mouth and intestinal tract of healthy as well as diseased people. Almost 

 constantly upon the scalp, hands and other portions of the body surface, in 

 milk and foodstuffs. 



Many saprophytic non-pathogenic and saphrophytic and pathogenic species 

 of Staphylococci have been isolated and described; most of the latter have very 

 rarely been found associated with disease in man and of these some appear to 

 have a selective affinity for certain organs of the body, similar to the predilec- 

 tion for certain organs, according to Rosenow, shown by streptococci. 



FIG. 10. STAPHYLOCOCCUS, PURE CULTURE. STAINED WITH METHYLENE BLUE. 

 (4 X eyepiece and Ma oil immersion objective.) 



Of the various organisms that infect man, Staphylococci are among the most 

 frequent offenders, and the vast majority of such infections .are caused by one 

 or other of the following: staphylococcus albus, staphylococcus aureus and 

 staphylococcus citreus. Practically, these are alike in all respects, except pig- 

 ment production. Staphylococcus albus produces a white pigment; aureus, a 

 pigment that varies from light golden yellow to deep brownish-yellow; citreus, 

 lemon or greenish-yellow pigment. Chromogenesis appears when colonies 

 develop on media in an aerobic atmosphere, under anaerobic conditions pigment 

 is not produced. Old cultures tend to lose their chromogenic power. 



55 



