66o Typhoid Fever 



Loffler* has found malachite green a very useful adjunct 

 to our means of differentiating the typhoid from other simi- 

 lar bacilli. 



For the purpose, 2^ 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 the addition of 2 per cent, of peptone, 5 

 per cent, of lactose, i per cent, of glucose, 0.5 per cent, of sodium sul- 

 phate, 2 per cent, of nitrate of potassium, and 3 per cent, of a 2 per cent, 

 solution of malachite green. 



In the medium the ordinary cocci and bacilli do not grow, 

 Gartner's bacillus and the paratyphoid bacillus b leave the 

 medium clear, but grow as a deposit at the bottom of the 

 tube; the typhoid bacillus destroys the green. If agar-agar 

 be added, the colonies are surrounded by a clear yellow zone. 

 The colon and other organisms grow slowly if at all. 



Not many workers were satisfied with the results obtained 

 by malachite green, nor were the results obtained uniform. 

 A careful study of the subject was made by Peabody and 

 Pratt, f who found great differences in the quality and reac- 

 tions of different malachite greens in the market. That with 

 which LofBer worked was commercially known as " 120." 

 They obtained three samples of this dye, which varied in 

 acidity between wide margins (0.2-1.0). Experimenting 

 with the different preparations, they found that the least 

 acid was the most useful preparation. The success of the 

 method, therefore, depends upon the adjustment of the 

 concentration of the dye to the reaction of the medium. 

 When this is done, malachite green becomes a valuable 

 adjunct to specific differentiation. Their studies of the 

 media led Peabody and Pratt to the invention of a new 

 method of isolating typhoid bacilli from the feces. Instead 

 of employing malachite green agar-agar directly for this 

 purpose, they first employ malachite green bouillon as an 

 " enriching" culture, and after eighteen to twenty-four hours' 

 growth in the incubator inoculate one or two large (20 cm. 

 diameter) Drigalski-Conradi plates, from which the colonies 

 can subsequently be picked out. 



Bile salts were first employed in culture-media by Lim- 

 bourgt and have been more or less popular ever since, 



| "Inst. hyg. Univers. Griefswald," see "Bull. Inst. Past.," iv, No. 9, 

 May 15, 1906, p. 393. 



* "Boston Med. and Surg. Journal," Feb. 13, 1908, CLVIII, p. 213. 

 f "Zeitschrift f. physiol. Chemie," 1889, m, p. 196. 



