652 Typhoid Fever 



Richardson* has found it very convenient to saturate filter-paper 

 with typhoid serum, dry it, cut into 0.5 cm. squares, and keep it on 

 hand in the laboratory for the purpose of making this differentiation. 

 To make a test, one of these little squares is dropped in 0.5 c.c. of a 

 twenty-four-hour-old bouillon culture of the suspected bacillus and 

 allowed to stand for five minutes. A drop .of the fluid placed upon 

 a slide and covered will then show typical agglutinations if the culture 

 be one of the typhoid fever bacillus. In a second mention of this 

 methodf he has found its use satisfactory in practice and the paper 

 serviceable after fourteen months' keeping. 



The Cultural Differentiation. When the typhoid bacilli 

 are to be isolated from the blood of living patients, they are 

 so likely to be obtained in pure culture that little trouble is 

 experienced. If they are to be isolated from the pus of a 

 posttyphoidal abscess, or from viscera at autopsy, from 

 water suspected of pollution, and especially when they are to 

 be isolated from the intestinal contents, with its rich bacterial 

 flora, the matter becomes progressively complicated. 



As the colonies of the typhoid bacilli closely resemble those 

 of Bacillus coli, etc., special media have, from time to time, 

 been devised for the purpose of emphasizing such differences 

 as rapidity of growth, acid production, etc. Thus, Eisner t 

 has suggested the employment of a special medium made as 

 follows : 



One kilogram of grated potatoes (the small red German potatoes 

 are best) is permitted to macerate over night in i liter of water. The 

 juice is carefully pressed out and filtered cold, to get rid of as much starch 

 as possible. The filtrate is boiled and again filtered. The next step is a 

 neutralization, for which Eisner used litmus as an indicator, and added 

 2.5 to 3 c.c. of a T V normal sodium hydrate solution to each.,10 c.c. of the 

 juice. Abbott prefers to use phenolphthalein as an indicator. The 

 final reaction should be slightly acid. Ten per cent, of gelatin (no pep- 

 tone or sodium chlorid) is dissolved in the solution, which is boiled, and 

 must then be again neutralized to the same point as before. After filtra- 

 tion the medium receives the addition of i per cent, of potassium iodid; 

 then it is filled into tubes and sterilized like the ordinary culture-media. 



When water or feces suspected of containing the typhoid bacillus are 

 mixed in this medium and poured upon plates, no bacteria develop well 

 except the typhoid and colon bacilli. 



These, however, differ markedly in appearance, for the colon colonies 

 appear of the usual size in twenty-four hours, at which time the typhoid 

 bacillus, if present, will have produced no colonies discoverable by the 

 microscope. 



It is only after forty-eight hours long after the colon colonies have 

 become conspicuous that little colonies of the typhoid bacillus appear 

 as finely granular, small, round, shining, dew-like points, in marked con- 

 trast to their large, coarsely granular predecessors. 



* "Centralbl. f. Bakt. u. Parasitenk.," 1897, p. 445. 



f "Journal of Experimental Medicine," May, 1898, p. 353, note. 



J "Zeitschrift fur Hygiene," xxn, Heft i, 1895; Dec. 6, 1896. 



