662 Bacillus Coli 



agglutinated the cultures obtained, not only from his own stools, but 

 from those of all the other cases. From this uniformity of action 

 Lesage suggests that the colon bacilli in these cases are all of the same 

 species. 



The agglutinating reaction occurs only in the early stages and 

 acute forms of the disease. 



Immunization. — It is not difficult to immunize an animal against 

 the colon bacillus. LofSer and Abel immunized dogs by progressively 

 increased subcutaneous doses of live bacteria, grown in solid culture 

 and suspended in water. The injections at first produced hard swell- 

 ings. The blood of the immunized animals possessed an active 

 bactericidal effect upon the colon bacteria. The serum was not in 

 the correct sense antitoxic. 



Differential Diagnosis. — This problem is considered at greater 

 length under the heading "Cultural Differentiation of the Bacillus 

 Typhosus " (q.v.). For the recognition of the colon bacillus the most 

 important points are the motihty, the indol-formation, the milk- 

 coagulation, and the active gas-production. As, however, most of 

 these features are shared by other bacteria to a greater or less degree, 

 the most accurate differential point is the immunity reaction with the 

 serum of an immunized animal, which protects susceptible animals 

 from the effects of inoculation, and produces a similar agglutinative 

 reaction to that observed in connection with the blood and serum of 

 typhoid patients, convalescents, and immunized animals. 



The fact that, with rare exceptions, the typhoid serum produces a 

 specific reaction with the typhoid bacillus, and the colon serum with 

 the colon bacillus, should be the most important evidence that they 

 are entirely different species. 



What is commonly known as Bacillus coli communis is, no doubt, 

 not a single species, but a group of bacilli too similar to be differen- 

 tiated into groups, types, or families by our present methods. 



In order to establish a type species of Bacillus coli communis. 

 Smith* says: 



"I would suggest that those forms be regarded as true to this species which 

 grow on gelatin in the form of delicate bluish or more opaque, whitish expansions 

 with irregular margins; which are actively motile when examined in the hanging 

 drop from young surface colonies taken from gelatin plates; which coagulate milk 

 within a few days; grow upon potato, either as a rich pale or brownish-yellow 

 deposit, or merely as a glistening, barely recognizable layer, and which give a 

 distinct indol reaction. Their behavior in the fermentation-tube must conform 

 to the following scheme: 



" Variety a: 



"One per cent, dextrose-bouillon (at 37°C.). Total gas approximately Kl 

 H : CO2 = approximately 2:1; reaction strongly acid. 



"One per cent, lactose-bouillon: as in dextrose-bouillon (with slight varia- 

 tions) . 



"One per cent, saccharose-bouillon; gas-production slower than the preceding, 

 lasting from seven to fourteen days. Total gas about ?i; H : CO2 = nearly 3 : 2. 

 The final reaction in the bulb may be slightly acid or alkaline, according to the 

 rate of gas-production (B. coli communior, Dunham). 



" Variety 13: 



*"Amer. Jour. Med. Sci.," 1895, no, p. 287. 



