CHAPTER V. 



STUDY AND IDENTIFICATION OF BACTERIA COCCI. 

 KEY AND NOTES. 



Streptococcus Forms. Cells divide to form chains. 



A. Gelatin not liquefied. 



1. Tendency to form long chains. 



a. Streptococcus pyogenes. (Cocci .7 to i /*.) 



b. Streptococcus anginosus. 



2. Tendency to form short chains. 



a. Streptococcus salivarius. 



b. Streptococcus fecalis. 



B. Gelatin liquefied. 



a Streptococcus coli gracilis. (Cocci quite small .2 to .4/1. In feces.) 

 Sarcina Forms. Cells divide in three dimensions of space. (Packets.) 



A. No pigment production on agar. 



a. Sarcina alba. (Colonies finely granular.) 



b. Sarcina pulmonum. 



B. Yellowish pigment. 



a. Sarcina lutea. (Colonies coarsely granular.) 



b. Sarcina flava. (Colonies finely granular.) 



C. Rose-red pigment. 



a. Sarcina rosea. 

 Micrococcus Forms. Cells divide irregularly in various directions. 



I. Gram positive cocci. 



A. Cocci round. 



1. Divide in two planes at right angles. Merismopedia. 



a. M. tetragenus. Moist viscid colonies. No liquefaction of 

 gelatin. Capsule. 



2. Divide irregularly. 



a. Gelatin not liquefied. M. cereus albus. 



h Pelatin linuefied I M. (Staphylococcus} pyogenes albus. 



b. O lique ed. J M (StaphyoIocccus ) pvog enes aureus. 



c. Gelatin very slightly liquefied. 



S. epidermidis albus. (Stitch coccus.) 



B. Cocci biscuit-shape. 



Diplococcus crassus. (May be mistaken for meningococcus.) 



C. Cocci lance shape. 



Diplococcus pneumoniae. Fraenkel's pneumococcus. Capsule. 



II. Gram negative cocci. 



A. Grow only about incubator temperature. 



1. Grow only on blood or serum media. Gonococcus. 



2. Grow on blood serum media, or glycerine agar. 



a. Diplococcus intracellularis meningitidis. (Produces acid in 

 glucose.) 



3. Grows on ordinary media. Micrococcus melitensis. 



B. Will grow at room temperature as well as at 37 C. 



a. Micrococcus catarrhalis. (Produces alkalinity in glucose media.) 



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