GRAM-NEGATIVE COCCI 



387 



OTHER GRAM-NEGATIVE COCCI 



Micrococcus phaiyngis siccus. — ^This organism was first described by 

 von Lingelsheim ' in 1906. It is described by Elser and Huntoon as 

 readily differentiable from meningococcus and other Gram-negative 

 cocci by the firm adherence and dryness of its colonies. It is similar to 

 Micrococcus catarrhalis from which it may, however, be differentiated 

 by fermentation tests. 



Diplococcus mucosus. — ^This organism was also described by von 

 Lingelsheim together with the preceding one. Its colony formation is 

 similar to that of meningococcus, but slightly more sticky and mucoid. 

 Stained by the capsule methods, it is seen to possess a distinct capsule. 



Chromogenic Gram-negative Cocci. — These microorganisms all pro- 

 duce a greenish-yellow pigment on the ordinary culture media. When 

 pigment is absent, as is frequently the case when grown upon sugar-free 

 media, these microorganisms can be distinguished from meningococcus 

 only by sugar fermentation and serum reactions. 



An exhaustive study of Gram-negative micrococci has recently 

 been made by Elser and Huntoon.^ These authors, in studying 

 the differential value of sugar fermentation in the diagnosis of these 

 bacteria, have constructed the following table: 



Strains Tested. 



Meningococcus 



Pseudomeningococcus 



Gonococcus 



Micrococcus catarrhalis 



Micrococcus pharyngis siccus . 



Chromogenic group I 



Chromogenic group II 



Chromogenic group III 



Jaeger meningococcus, Krai . , 

 Diplococcus crassus, Krai . . . . 



' V. Lingelsheim, Klin. Jahrb., 15, 1906. 



2 Elser and Huntoon, loc. cit. 



