COLON BACILLUS 



127 



Morgan has reported as the cause of certain cases of bacillary dysen- 

 tery a bacillus known as B. Morgan, No. i. It is motile, produce indol, 

 and in glucose bouillon gives a very slight amount of gas. 



It does not change mannite and does not produce a primary acidity in litmus 

 milk. This organism is a frequent cause in England of summer diarrhoea of 

 children. Flies from houses with such cases often show Morgan's bacillus. A 

 dysentery type much like the Flexner-Strong strain is often found in the enteric 

 affections of children in the United States. 



In Japan, dysentery-like epidemics of a very fatal disease, termed 

 ekiri, occur among young children. The organism is very motile, pro- 

 ducing gas and acid in glucose but not in lactose media. It is reported 

 at times to show indol production. Apparently a member of the Gart- 

 ner group. 



More recently a strain of dysentery bacilli, known as Type Y, has been con- 

 sidered of importance. This organism is very closely related to the Flexner strain 

 and only differs from it in that it requires about forty-eight hours to turn mannite 

 litmus media pink and that maltose litmus remains blue. An organism showing 

 similar cultural characteristics has been recently recovered from faeces of laboratory 

 rabbits by German workers investigating the problem of whether certain animals 

 might serve as carriers for dysentery. 



B. COLI, B. LACTIS AEROGENES, B. CLOACA 



While the COLON BACILLUS chiefly inhabits the large intestine, the B. 

 lactis aerogenes is to be found in the upper part of the small intestine. 

 While they may be separated on the ground of motility, yet it is by the 

 greater fermentative activity of the B. lactis aerogenes that they are 

 best separated. Some consider them as only representing different 

 strains of the same organism. 



The main points of distinction are gas production in starch media (gas bubbles 

 on potato slant) and frequent nonproduction of indol. B. lactis aerogenes is closely 

 related to the pneumobacillus and at times shows capsules. It is best differentiated 

 from the pneumobacillus by its gas production in lactose and coagulation of milk. 



Some consider that the B. coli produces a bactericidal substance which 

 inhibits the growth of, or destroys, pathogenic bacteria which may have 

 passed the destructive influences of the gastric juice; others that this 

 effect is due to their free growth and the development of phenol and 

 various putrefactive substances. 



The probable importance of the colon bacillus in protecting the ^organism is 

 shown by the fact that where numerous colonies of pathogenic organisms may be 



