620 Bacillus Coli 



Virulence. — It is a question whether the colon bacillus is always 

 virulent, or whether it becomes so under abnormal conditions. 

 Klencki* found it very virulent in the ileum, and less so in the colon 

 and jejunum of dogs. He also found that the virulence was greatly 

 increased in a strangulated portion of intestine. Dreyfusf found 

 that the colon bacillus as it occurs in normal feces is not virulent. 

 Most experimenters believe that pathologic conditions, such as 

 disease of the intestine, strangulation of the intestine, etc., increase 

 its virulence. 



Frequent transplantation lessens the virulence of the bacillus; 

 passage through animals increases it. 



It has been observed that cultures of the bacillus obtained from 

 cases of cholera, cholera nostras, and other intestinal diseases are 

 more pathogenic than those obtained from normal feces or from pus. 



Adelaide Ward Peckham,J in an elaborate study of the "Influence 

 of Environment on the Colon Bacillus," concludes that while the con- 

 ditions of nutrition and development in the intestine seem to be most 

 favorable, the colon bacillus is ordinarily not virulent. She says: 



"Its first force is spent upon the process of fermentation, and as long as oppor- 

 tunities exist for tlie exercise of this function the affinities of this organism appear 

 to be strongest in this direction. 



"Moreover, the contents of the intestine remain acid until they reach the 

 neighborhood of the colon, and by that time the tryptic peptones have been 

 formed and absorbed to a great extent. 



"During the process of inflammation in the digestive tract a very different 

 condition may exist. The peptic and tryptic enzymes may be partially sup- 

 pressed. Fermentation of carbohydrates and proteid foods then begins in the 

 stomach, and continues after the mass of food is passed on into the intestine. 

 The colon bacillus cannot, therefore, spend its force upon fermentation of sugars, 

 because they are already broken up and an alkaline fermentation of the proteids 

 is in progress. It also cannot form peptones from the original proteids, for it does 

 not possess this property, and unless trypsin is present it must be dependent upon 

 the proteolytic activity of other bacteria for a suitable form of proteid food. 

 Perhaps these bacteria form an albuminate molecule which, like leucin and 

 tyrosin, cannot be broken up into indol, and thus there might be caused an im- 

 portant modification of the metabolism of the colon bacillus, which might have 

 either an immediate or remote influence upon its acquisition of disease-producing 

 properties, for our own experiments indicate that the power to form indol, and 

 the actual forming of it, are to some extent an indication of the possession of 

 pathogenesis." 



For the laboratory animals the colon bacillus is pathogenic in 

 varying degree. Intraperitoneal injections into mice cause death 

 in from one to eight days if the culture be virulent. Guinea-pigs 

 and rabbits also succumb to intraperitoneal and intravenous in- 

 jection. Subcutaneous injections are of less effect, and in rabbits 

 produce abscesses only. 



When injected into the abdominal cavity, the bacilli set up a sero- 

 fibrinous or purulent peritonitis, and are very numerous in the ab- 

 dominal fluids. 



* "Ann. de ITnst. Pasteur," 1895, No. 9. 

 t "Centralbl. f. Bakt.," etc., xvi, p. 581. 

 t "Journal of Experimental Medicine," Sept., 1897, vol. n, No. 4, p. 549- 



