568 Bacilli Resembling the Typhoid Bacillus 



Nitrates are reduced to nitrites by the growth of the 

 bacillus. 



In bouillon containing i per cent, of dextrose, lactose, 

 and saccharose, the colon bacillus splits up the sugar, lib- 

 erating CO 2 and H, the gas formula being ^ = -f-. This 

 gas formula is very constant for the micro-organisms of the 

 colon group and forms one of their most important differ- 

 ential characteristics. In sugar-containing bouillon acetic, 

 lactic, and formic acids are produced. 



The bacillus requires very little nutriment. It grows in 

 Uschinsky 's asparagin solution, and is frequently found living 

 in river and well waters. 



Indol is formed in both bouillon and peptone solutions, 

 but phenol is not produced. The presence of indol is best 

 determined by Salkowski's method (q. v.). 



Toxic Products. Vaughan and Cooley* have shown 

 that the toxin of the colon bacillus is contained in the 

 germ-cell and under ordinary conditions does not diffuse 

 from it into the culture medium. The toxin may be heated 

 in water to a very high temperature without injuring its 

 poisonous nature. They have devised an apparatus in 

 which enormous cultures can be prepared and the bacteria 

 pulverized. f Of such a preparation 0.0002 gram will kill a 

 2OO-gram guinea-pig. 



Pathogenesis. The bacillus begins to penetrate the 

 intestinal tissues almost immediately after death, and is the 

 most frequent contaminating micro-organism met with in 

 cultures made at autopsy. It may spread by direct con- 

 tinuity of tissue, or ma the blood-vessels. 



Although under normal conditions a saprophyte, the 

 colon bacillus is not infrequently found in the pus in sup- 

 purations connected with the intestines as, for example, 

 appendicitis and sometimes in suppurations remote from 

 them. 



In intestinal diseases, such as typhoid, cholera, and 

 dysentery, the bacillus not only seems to acquire an unusual 

 degree of virulence, but because of the existing denudation 

 of mucous surfaces, etc., finds it easy to enter the general 

 system, with the formation of remote secondary suppura- 

 tive lesions in which it is the essential factor. When ab- 



*"Jour. Amer. Med. Assoc.," 1901; and "American Medicine," 

 1901. 



t "Trans. Assoc. Amer. Phys.," 1901. 



