CHAPTER XXIV 



PNEUMONIA, MENINGITIS AND GONORRHEA— THE SPE- 

 CIFIC PYOGENIC COCCI— THE GENERA DIPLOCOCCUS 



AND NEISSERIA 



The organisms belonging to the genera Diplococcus and 

 Neisseria include for the most part pathogenic, or at least 

 parasitic bacteria, spherical in shape, whose cells occur 

 generally in pairs. 



The organisms may be differentiated by use of the Gram 's 

 stain. The members of the genus Diplococcus are Gram- 

 positive, those of the Neisseria Gram-negative. The organ- 

 isms belonging in this group which are pathogenic and of 

 economic importance are three in number: the Diplococcus 

 pneumonice, causing pneumonia ; the Neisseria meningitidis, 

 causing infectious cerebrospinal meningitis in man, and the 

 Neisseria gonorrhcece, causing the disease gonorrhea in man. 



These organisms include the most common forms of the 

 so-called specific pyogenic cocci, that is, those cocci re- 

 sponsible for inflammatory changes in connection with 

 specific diseases. 



Diplococcus pnetjmonls; 



Sjmonyms. — Streptococcus pneumonia, Diplococcus lan- 

 ccolatus. 



The organism is usually termed the pneumococcus. 



The term pneumonia literally designates an inflammation 

 of the lungs. This may be caused by any one of several 

 species of bacteria. In the great majority of cases the 

 pneumococcus is the cause and is ordinarily spoken of or 

 referred to as the cause of speciflc infectious pneumonia. 



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