134 BACTERIOLOGY OF MEAT AND MEAT PRODUCTS 



Care must be taken to accurately label everything and to 

 note any points in regard to selection, i.e. if samples taken from 

 outside or inside of a larger piece, etc. 



The material must of course be transmitted at once, properly 

 sealed, and, if any delay is likely, sent in ice-boxes. 



2. Bacteriological examination. 



A. The suspected foodstuffs. The precise methods of exami- 

 nation will of course vary slightly with the nature of the food,, 

 but should be on the following lines : 



The physical appearance and smell should be carefully 

 noted. Any deviations from the natural appearance of normal 

 food of the kind under examination should be particularly noted;, 

 for example slight liquefaction. 



Aerobic and anaerobic cultivations, feeding and inoculation 

 tests, may all have to be made. 



Mice should be fed with portions of the sample 1 , while other 

 animals e.g. guinea-pigs should be inoculated subcutaneously 

 and intraperitoneally from cultures and also from the broth 

 emulsions of the food. If any of the animals die, a complete 

 post-mortem examination should be made. 



For cultural examination it is important to obtain a uniform 

 and characteristic sample. This can be conveniently done by 

 mincing up selected portions with sterile instruments and adding 

 to sterile water or broth in a flask, mixing thoroughly. If a 

 quantitative examination is to be made a definite quantity of 

 food must be added to a definite quantity of water. A fairly 

 complete examination would include examination for Gaertner 

 group bacilli, Proteus group bacilli, B. coli and allied organisms 

 and for anaerobic bacilli such as B. botulinus. 



The most reliable method, in the writer's opinion, to isolate 

 Gaertner group bacilli is to brush some of the emulsion directly 

 over a series of lactose, neutral red bile salt agar plates (L.B.A.) 

 and to also add some of the emulsion to dulcite malachite 



1 While it is a simple and useful procedure to examine mice the greatest caution 

 should be used in interpreting the results. Mice not infrequently are carriers of 

 Gaertner group bacilli and when fed, even with sterile food, may die and Gaertner 

 group bacilli be isolated post-mortem. Feeding mice is chiefly of value from the 

 negative aspect. 



