BACTERIOLOGY OF MEAT AND MEAT PRODUCTS 133 



suipestifcr or B. paratypJwsus (3 has either no power of agglutina- 

 tion or will only agglutinate them in dilutions far lower than 

 those which cause rapid agglutination with B. enteritidis. In 

 the same way the sera of animals immunised against these two 

 organisms exert comparatively slight agglutination action upon 

 B. enteritidis. 



B. suipestifer and B. paratyphosus (3 often, but not regularly, 

 show slight agglutination differences, but by the use of absorption 

 tests definite differences can be made out. 



The bacteriological investigation of food poisoning outbreaks. 



It is very desirable that all food poisoning outbreaks should 

 be bacteriologically investigated even if limited to one or two 

 families. Usually, at the present day, if any examination at all 

 is made the material is sent to a chemist and a chemical exami- 

 nation is made for poisonous metals or ptomaines. Naturally 

 such examinations are negative and the true source of the 

 outbreak is overlooked. 



I. Collection and transmission of material. 

 The following, if available, should all be sent : 



(a) The supposed incriminated food or foods. Samples 

 should be obtained not only at the source of supply (shop, place 

 of preparation, etc.), but also from the homes of the sufferers. The 

 latter is most important, as from these sources the bacteriologist 

 is much more likely to obtain portions actually infected. 



(b) Material from autopsies on fatal cases. This is of 

 course extremely important, and such material is both easier to 

 work with and far more likely to show the bacillus concerned in 

 the infection than is the suspected food. 



The materials most valuable to examine are pieces of liver, 

 the spleen and portions of bones (for bone marrow). A piece 

 of intestine, ligatured to retain its contents, is also useful. 



(c) Blood serum from persons who have been attacked. 

 A good many different specimens should be collected. Some- 

 times, particularly if serum cannot be obtained, it is valuable to 

 examine the urine and excreta of such cases. 



