CHAPTER XII 
MICROCOCCUS CATARRHALIS AND GRAM- 
NEGATIVE COCCI 
I. Micrococcus Catarrhalis 
This is an organism found in inflammation of upper 
respiratory tract. Its significance is unimportant except 
that being a Gram-negative diplococcus, it can not be 
differentiated in its appearance from gonococci and men¬ 
ingococci; from gonococcus it differs by growing on sim¬ 
ple meat extract media. It is much more difficult to dif¬ 
ferentiate it from meningococcus, and yet it is especially 
important as both are usually found in the nose. It grows 
much better on simple media than the meningococcus, its 
colonies are coarse while those of meningococcus are very 
fine, and micrococcus will grow below 25° C., while the 
meningococcus will not. 
II. Gram-negative Cocci 
Gram-negative cocci producing green pigment can be 
separated from the gonococcus and meningococci by sugar 
fermentation and agglutination. 
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