TEST FOR TYPHOID BACILLUS 



105 



fication of the germ. The proceedings are similar to those out- 

 lined for the colon bacillus, excepting that in this case the quan- 

 titative factor is not considered. The finding of a single typhoid 

 fever germ in a mass of food materials is sufficient to condemn it. 

 It may be assumed that where there is one typhoid bacillus there 

 are more in the same vicinity and these may initiate an epidemic 

 of typhoid fever. 



The food bacteriologist may be called upon to examine food 

 substances for the presence of typhoid contamination (from the 

 feces of typhoid patients or of carriers) in instances where it is 

 known that food has been exposed to typhoid infection or where 

 such infection is merely suspected. The isolation from foods and 

 the positive identification of the typhoid bacillus is by no means a 

 simple matter. It is necessary to make use of special cultural 

 methods, supplemented by the agglutination test, etc. The 

 methods tried out by various bacteriologists are too numerous to 

 even review and most of them have after a time been abandoned 

 as unsatisfactory. The following tabulation from the work of 

 Prescott and Wilson indicates some of the more practical laboratory 

 procedures which have been tried with more or less success. 



Examination of 



water for typhoid 



bacilli 



i. Physical concen- 

 tration 



2. Enrichment 



3. Isolation 



4. Identification. 



a. By filtration. 



b. By agglutination 



ISchuder's j 

 Fischer's I Proc- 

 Wilson's | ess. 

 Muller's j 



a. Hoffman and Picker's caffein process. 



b. Jackson's lactose bile. 



c. Parietti's carbol broth. 



a. Eisner's gelatin medium. 



b. Endo's medium. 



c. LoefBer's malachite green medium. 



d. Drigalski-Conradi agar. 



e. Hiss's medium. 

 /. Hesse's medium. 



a. Morphological and cultural charac- 



teristics. 



b. Agglutination. 



