PART III 



CHAPTER XV 



THE PYOGENIC COCCI 



THE microorganisms most frequently found in suppurative 

 processes, such as boils, abscesses, and purulent inflammations, 

 belong to a group of bacteria known as pyogenic cocci. Of these 

 the two most important because of their virulence and frequent 

 occurrence are Staphylococcus (pyogenes) aureus and Streptococcus 

 pyogenes. 



Early investigators noticed the frequent presence of small 

 round bodies in the pus discharged from abscesses and sinuses 

 and gave to them a variety of names. In 1880 staphylococci 

 were first obtained from pus by Pasteur. In 1881 Ogston studied 

 the question and found that the staphylococci were most common 

 in circumscribed acute abscesses and the streptococci in spreading 

 suppurative conditions. Rosenbach in 1884 differentiated by 

 means of cultures several different varieties of pyogenic micro- 

 cocci to which he gave the special names staphylococcus pyogenes 

 aureus, staphylococcus pyogenes aJbus, streptococcus pyogenes, etc. 

 Other organisms are met with less frequently in suppuration ; 

 such for example as staphylococcus pyogenes citreus, micrococcus 

 tetragenus, bacillus pyocyaneus, etc. The pyogenic cocci are con- 

 stant inhabitants upon the skin and mucous membranes. Conse- 

 quently not only may they cause a pathogenic condition themselves 

 but may readily enter into an infection started by another organism 

 and further increase the injury by giving rise to a " mixed infec- 

 tion." 



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