656 ■ Bacillus Coli 



Gwyn,* Libman,t Gushing, J Durham,! Savage and Read,|| Rus- 

 sell,** Krumwiede, Pratt and McWilliamsft and many others have 

 studied these organisms from various points of view. The impor- 

 tant points are to recognize their presence in cases of suspected in- 

 fection and to differentiate them quickly from the typhoid and 

 dysentery bacilli. 



RussellH first plated the material to be examined on Endo's plated 

 medium, and then transplanted the suspicious colonies to a tube of 

 culture-media so arranged as to contain two sugars that were incon- 

 siderably mixed. About 5 cc. of glucose litmus agar-agar were put 

 into each tube, and after sterilizing and cooling, enough sterilized 

 lactose litmus agar-agar was added to make a good slant. The 

 tubes were then incubated over night to permit any contaminating 

 organism to grow. The glucose-agar is at the bottom, the lactose 

 agar forms the surface, the tube is inoculated by stroking the surface 

 and stabbing the agar. In this way both media are brought into 

 use. Typhoid cultures thus inoculated after eighteen hours show 

 the usual non-spreading colorless growth on the surface of a blue 

 background of unchanged medium. In the depth of the tube, how- 

 ever, the medium is changed to a bright uniform red color. Later 

 Russell found that it was not necessary to keep the media separated, 

 but that thje sugar could be added to the agar-agar containing litmus 

 and enough sodium hydrate to make the mixture just neutral to the 

 litmus. Last of all o.i per cent, of glucose and i.o per cent, of lac- 

 tose are added and the mixture sterilized. The autoclave should 

 not be employed for the sterilization because the high temperature 

 tends to break down the lactose. In such a tube the typhoid bacil- 

 lus causes a colorless surface growth upon a blue background with 

 a red color in the bottom of the tube when punctured. 



There is no gas. The colon bacillus, on the other hand, produces 

 abundant gas, and the medium is reddened throughout. The 

 dysentery bacillus behaves like the typhoid. The paratyphoids ap- 

 pear like the typhoid on the surface, but in the lower part of the punc- 

 ture made in the medium, a few gas bubbles appear. 



Krumwiede and Kohn§§ have found that if Andrade's indicator is 

 employed instead of litmus, three sugars, glucose, lactose and sac- 

 charose may all be added to the same agar-agar and the separation 

 of the "intermediates" facilitated by observing the fermentation 

 produced. To this end they use a stock agar made as follows: 



* "Johns Hopkins Bulletin," 1898, vol. ix. 



t "Journal of Medical Research," 1902, viii, p. 168. 



t "Johns Hopkins Bulletin," 1900, vol. xi. 



§ "Journal of Experimental Medicine," 1901, vol. v, p. 353. 



II Journal of Hygiene, 1913, xiii, 343. 

 ** Jour. Med. Research, igii,xxv, 217. 

 tt Jour. Infectious Diseases, 1916, xvni, i. 

 tt Jour. Med. Research, i9i2,xxv, p. 217. 

 §§ Jour. Med. Research, 1917, xxxii, p. 225. 



