650 Typhoid Fever 



Dissolve the agar-agar in 500 cc. of the water over a free flame, making up the 

 loss by evaporation. Dissolve the other ingredient, in the remaining 500 cc. 

 of water, heat until dissolved, replacing the loss by evaporation.. Pour the two 

 solutions together, heat for thirty minutes and add distilled water to_ replace loss 

 by evaporation. Filter through cotton until clear. Adjust reaction to i per 

 cent, acidity. Tube — 10 cc. to a tube. Sterilize in the autoclave. 



The medium is used for plating. The material containing the 

 micro-organisms must be so dilute that only a few colonies will 

 develop upon the plates. The typhoid colonies greatly outgrow the 

 colon colonies and may attain to a dianieter of several centimeters. 

 They show a small opaque center and an opalescent body and appear 

 circular. 



Capaldi* recommends the following medium for plating typhoid 

 and colon colonies: 



Witte's peptone 20 grams 



Gelatin 10 grams 



Agar-agar 20 grams 



Dextrose or mannite 10 grams 



Sodium chlorid S grams 



Potassium chlorid 5 grams 



Distilled water 1000 grams 



Dissolve the agar in 500 cc. of water, the other ingredients in the other 500 cc. 

 of water. Pour together, add 10 cc. of NaOH, filter, and tube. 



Upon this medium the typhoid colonies are small, glistening 

 bluish, and translucent. Colon colonies are larger, opaque, and 

 brownish. 



Endof recommends the employment of the following medium upon 

 which colonies of the typhoid bacillus grow large and remain colorless 

 while those of the colon bacillus remain small and red; 



1000 cc. of meat infusion. 

 30 grams of agar-agar. 

 10 grams of peptone (Witte's). 

 S grams of sodium chlorid. 



Neutralize to -f-i, and clear by filtration. Distribute the medium in 150 cc. 

 flasks and sterilize in the autoclave. When the medium is to be used, have ready a 

 10 per cent, solution of basic fuchsin in 95 per cent, alcohol that has stood for 20 

 hours and been decanted, and also a 10 per cent, solution of anhydrous sodium sul- 

 phite. To 10 cc. of the latter solution add 2 cc. of the former and steam the mix- 

 ture in an Arnold sterilizer for five minutes. To each 100 cc. of the agar-agar add 

 I gram of pure lactose, dissolve in streaming steam or on a water-bath and then 

 add J^ cc. of the fuchsin-sulphite solution. The medium is then ready for use 

 in Petri dishes into which it can be poured as soon as mixed with the water, or 

 without admixture, to be inoculated later by stroking with a platinum wire. The 

 bleaching of the fuchsin by the sulphite should result in a nearly colorless 

 medium. 



LofflerJ has found malachite green a very useful adjunct to our 

 means of differentiating the typhoid from other similar bacilli. 



For the purpose, 2 J^ to 3 per cent, of a 2 per cent, solution of malachite green are 

 added to the culture-medium. The preparation given the preference consists of i 

 pound of meat macerated in i liter of water, neutralized with potassium, with 



* "Zeitschrift fiir Hygiene," 1896, xxm, 475. 



t "Centralbl. f. Bakt.," etc., 1904, xxxv. 



t "Boston Med. and Surg. Journal," Feb. 13, 1908, CLvm, p. 213. 



