CHAPTER XXI 



NON-SPECIFIC PYOGENIC COCCI 



THE non-specific pyogenic cocci are characteristic of wound 

 infections, suppuration, non-specific inflammations, and their 

 sequelae. A considerable number of microorganisms have been 

 described belonging to this group. They are found quite com- 

 monly upon the surface of the skin. In pathogenicity, they vary 

 from non-virulent strains to those which will kill experimental 

 animals promptly when introduced in minute doses. Even the 

 same organism may be made to vary its virulence by proper 

 cultural methods. 



An organism which is capable of causing suppuration or pus 

 production is said to be pyogenic. A long list of organisms are 

 known which can bring about this tissue reaction, but the coccal 

 forms to be studied are by far the most common in suppurative 

 processes in man and animals. Whenever these organisms invade 

 the tissues, or are introduced through a wound, they begin to 

 multiply and to destroy, and seemingly, to some extent, to dis- 

 integrate the tissues with which they are in contact. The body 

 reacts, in general, by an inflammation of the surrounding tissues, 

 the blood-vessels become dilated, there is more or less extravasa- 

 tion of blood-serum. Most important of all, the phagocytic 

 white blood-cells, particularly the polymorphonuclear leukocytes, 

 pass out of the capillaries in great numbers, so that the tissues 

 become packed full and the lesion is surrounded by a phagocytic 

 wall, which usually effectually prevents the bacteria from spread- 

 ing. The leukocytes also invade the diseased tissue and eventually 

 destroy the bacteria. This can, of course, be accomplished only 

 in the presence of opsonins. Nor is it brought about without 

 a struggle, for many of the leukocytes themselves are destroyed by 

 the bacteria, possibly through the leukocytotoxic substances 



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