Differentiation of Typhoid and Colon Bacilli 651 



eighteen- to twenty-hour-old culture of virulent typhoid bacilli 

 were washed with 4 to 5 c.c. of sterile water. The suspension 

 thus obtained was heated to 60 C., centrifugated, and the 

 supernatant fluid withdrawn. The centrifugated organisms 

 were then dried and triturated. A second suspension of these 

 broken up bacillary bodies was then made, and allowed to 

 stand for from two to three days at 60 C. The extract 

 thus obtained, after removing the disintegrated and digested 

 remnants, was precipitated with alcohol, forming a fine coag- 

 ulum. This was subsequently dried and powdered and dis- 

 solved in sterile water in the proportion of 0.02 mg. to a 

 drop."* 



When one drop of this is placed upon the conjunctiva 

 of a patient in the early days of typhoid fever, diffuse 

 redness increases and becomes marked in two or three hours. 

 There is also some feeling of heat in the eye. Tears flow 

 freely, and there is a slight mucopurulent exudate in some 

 cases. The reaction persists about ten hours and then 

 declines, usually disappearing in twenty-four hours. Ham- 

 burger f confirmed the results of Chantemesse. It is too 

 early to say how useful the reaction is, but it seems to 

 promise aid in diagnosing difficult cases. 



Differential Diagnosis of the Typhoid and Colon 

 Bacilli. This constitutes the chief perplexity of bacterio- 

 logic work with the typhoid bacillus, and is the great bugbear 

 of beginners. A great deal of energy has been expended upon 

 it, a considerable literature has been written about it, and 

 much still remains to be learned by which it may be simplified. 



Two chief methods are in vogue at present: 



1. The serum differentiation. 



2. The culture differentiation. 



Serum Differentiation. The specific agglutinating action 

 of experimentally prepared serums can be used to differentiate 

 cultures of the colon, paracolon, typhoid, and paratyphoid 

 bacilli, the typhoid bacilli alone exhibiting the specific effect 

 of the typhoid serum. This is a very reliable means of differ- 

 entiation when the cultures have already been isolated. The 

 method is described under the heading "Agglutination," in 

 the section devoted to the "Special Phenomenon of Infection 

 and Immunity." 



* See Hamburger, "Jour. Amer. Med. Assoc.," L, 17, p. 1344, April 25, 

 1908. 



f Loc. cit. 



