638 



PATHOGENIC MICROORGANISMS 



It is distinguished from the Colon bacillus chiefly by the fact that it 

 is less motile, hardly ever forms chains, and, when cultivated upon 

 suitable media, especially milk, it possesses a distinct capsule. It 

 differs from other forms of the Colon group in not fermenting 

 dulcite, and differs from B. acidi-lactici in fermenting saccharose. It 

 ferments with gas production, dextrose, lactose, saccharose, mannite 

 and raffinose. It produces indol, reduces nitrate, possesses either 

 no motility, or is very slightly motile. It coagulates milk, and when 

 grown on milk or lactose bile it often makes a stringy viscous cult- 

 ure, On agar and gelatin it makes heavy white colonies of a some- 



1 2 3 



FIG. 67. BACILLUS COLI COMMUNIOR. Grown in: 1. Dextrose, 2. Lactose, 3, 



Saccharose broth. 



what mucoid appearance, certainly more mucoid than most colon 

 colonies. It does not liquefy gelatin. In broth it causes general cloud- 

 ing with later a pellicle, and a sour odor. It grows heavily on potato. 



It is a facultative anaerobe and grows at room temperature. 



Varieties have been described depending upon minor cultural char- 

 acteristics which have no particular importance in this connection. 



The pathogenicity of Bacillus lactis aerogenes for man is slight. 

 Its chief claims to importance lie in its milk-coagulating properties 

 and its almost constant presence in the human intestine. In infants, it 

 may give rise to flatulence and it has been occasionally observed as the 

 sole incitant of cystitis. Among such cases rare instances have been 



