160 PATHOGENIC BACTERIA 



and up the rectum. The colon contains most of the bacilli 

 and the number decreases upward in the small intestine 

 until in the stomach they are rarely found. They may, 

 however, at times enter the liver by means of the bile pas- 

 sages or portal vein system. 



The consistency with which the colon bacilli are present 

 in the intestine raises the question as to their function or 

 value there. This is probably best answered today by saying 

 that they assist in controlling the growth of certain putre- 

 factive bacteria, and that they may assist somewhat in 

 breaking up simple substances so that these may be more 

 easily absorbed. 



The toxin of the colon bacillus is within its body, no extra- 

 cellular poison being formed. If one inject the dead organism 

 into an animal in sufficient number, mucous membrane irri- 

 tation, paralyses, and convulsions may occur. Living bacilli 

 introduced into the peritoneum cause peritonitis and septi- 

 cemia, the organisms entering the blood stream. An abscess 

 will usually result if they are brought under the skin. In 

 man colon bacilli seldom go beyond the mucous membrane 

 of the intestine because of the resistance offered by that tissue. 

 After death the organisms rapidly invade the different organs 

 of the body. Whenever the resistance of the body is reduced 

 an opportunity is presented for the spread of these organisms. 

 When for any reason the colon bacillus gains in virulence or 

 the resistance of the intestinal wall decreases, there arise 

 inflammation of the mucous membrane of the intestine, a 

 swelling of Peyer's plaques comparable to that seen in typhoid 

 fever, and these changes permit the bacteria to spread in the 

 body. There may arise inflammation of the gall-bladder, the 

 pelvis of the kidney, or abscesses in various parts of the body. 

 Cystitis may occur, which may be a part of a general infec- 

 tion, descend from the kidney, or arise from introduction of 

 the organisms through the urethra. An ascending infection 

 from the bladder to the pelvis of the kidney and on into the 

 substance of the organ is not an uncommon disease process. 



