Bacilli Resembling the Typhoid Bacillus 621 



Cumston,* from a careful study of 13 cases of summer infantile diar- 

 rheas, comes to the following conclusions: 



Bacterium coli seems to be the pathogenic agent of the greater number of sum- 

 mer infantile diarrheas. 



The organism is often associated with Streptococcus pyogenes. 



The virulence, more considerable than in the intestine of a healthy child, is 

 almost always in direct relation to the condition of the child at the time the cul- 

 ture is taken, and does not appear to be proportionate to the ulterior gravity of 

 the case. 



The mobility of Bacterium coli is, in general, proportionate to its virulence. 

 The jumping movement, nevertheless, does not correspond to an exalted virulence 

 in comparison with the cases in which the mobility was very considerable, without 

 presenting these jumping movements. 



The virulence of Bacterium coli found in the blood and other organs is identical 

 with that of Bacterium coli taken from the intestines of the same individual. 



Lesage,f in studying the enteritis of infants, found that in 40 out 

 of 50 cases depending upon Bacillus coli the blood of the patient 

 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. Loffler and Abel immunized dogs by progressively 

 increased subcutaneous doses of live bacteria, grown in solid cul- 

 ture and suspended in water. The injections at first produced hard 

 swellings. 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 motility, 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, 



* "International Medical Magazine," Feb., 1897. 

 f "La Semaine Me"dicale," Oct. 20, 1897. 



