Bacteriologic Methods 645 



The Isolation of the Bacillus from the Feces. — This method of 

 making the diagnosis has practically been abandoned because of its 

 uncertainty, its cumbersomeness, its tediousness, and because the 

 preceding methods suffice in all cases. 



An excellent resume of the many methods employed for isolating 

 the bacillus from the stools has been published by Peabody and 

 Pratt,* and is appropriate reading for those interested in this 

 subject. 



The Conjunctival Reaction. — An additional aid to the diagnosis of 

 typhoid, in doubtful cases, based upon the Wolff-Eisner-Calmette 

 reaction in tuberculosis, is the "ocular typhoid reaction" of Chan- 

 temesse.f This test consists in the instillation into the eye of a 

 solution made by extracting the typhoid bacillus as follows : " Gela- 

 tin plates covered with an eighteen to twenty-four 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 6o°C., centrifugated, 

 and the supernatant fluid withdrawn. The centrifugated organisms 

 were then dried and triturated. A second suspension of these 

 broken up baciUary bodies was then made, and allowed to stand for 

 from two to three days at 6o°C. The extract thus obtained, after 

 removing the disintegrated and digested remnants, was precipitated 

 with alcohol, forming a fine coagulum. This was subsequently 

 dried, powdered and dissolved in sterile water in the proportion 

 of 0.02 mg. to a drop." J 



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 mucopuru- 

 lent exudate in some cases. The reaction persists about ten hours 

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

 burger§ 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 bacteriologic 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 simphfied. 

 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 



* "Boston Medical and Surgical Journal," 1907. 



t "Deutsche med. Wochenschrift," 1907, No. 31, p. 1264. 



t See Hamburger, "Jour. Amer. Med. Assoc," l, 17, p. 1344, April 25, 1908. 



§ Loc. cit. 



