CHAPTER XII 

 MICROCOCCUS CATARRHALIS 



The micrococcus catarrhalis is identical in appearance with the gonococcus 

 and meningococcus and, like them, is Gram negative. It has only been found 

 so far on the mucous membrane of the respiratory passages and in the sputum of 

 some cases of pulmonary tuberculosis and lobar pneumonia patients. The 

 organism has feeble pathogenic power and may cause catarrhal inflammations. 

 It is of interest chiefly because it may be mistaken for the meningococcus. 

 These organisms are easily distinguished by culture. 



While it grows best at 37C., the micrococcus catarrhalis will grow at any 

 temperature down to 2oC.; the meningococcus will not grow below 25. The 

 micrococcus catarrhalis grows well on all the ordinary culture media, on gelatin, 

 agar and blood serum incubated at 37C., pin-head-sized, round, irregular- 

 edged, white colonies form in 24 hours. In plain bouillon there is cloudiness 

 with a fine white precipitate. Milk is not coagulated, sugars are not fermented. 



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