7 6 MEDICAL BACTERIOLOGY 



SARCINA 



Sarcina are occasionally found in the mouth and sputum of healthy persons, 

 more frequently when some chronic disease of the respiratory tract, as tuber- 

 culosis, exists. They are frequently present on foodstuffs exposed to air, dust 

 and handling, and in certain foods, as eggs, undergoing putrefaction. Some 

 forms are commonly present in air and soil. 



Of the five varieties sarcina may be divided into according to the color of 

 their growth on culture media: 



Sarcina pulmonum (colorless). 



Sarcina alba, and cervina (white). 



Sarcina lutea, flava, and lactis (yellow). 



Sarcina erythromyxa, (red). 



Sarcina aurantiaca (orange). 

 None are pathogenic for man. 



Morphology. Sarcina are non-motile cocci about the size of staphylococci. 

 They multiply by cell division in three directions and cocci remain united after 

 fission, so they are arranged in cubes each surface of which presents four cocci 

 or multiples of four. The appearance of these packets is often suggestive of a 

 bale of cotton. 



Staining. Sarcina stain readily with all the common dyes and are Gram 

 positive. 



Growth appears, under aerobic conditions, at 37C. in 24 to 72 hours on all 

 the ordinary media. 



Most strains do not coagulate milk; a few show acid but not gas production 

 in glucose media, usually sugars are not acted on. 



