BACTERIOLOGY OF MEAT AND MEAT PRODUCTS 131 



does not coagulate milk. All the cultures have a rancid butyric 

 acid odour. It produces a very powerful toxin, but, like the 

 tetanus bacillus, has but little power of development in the 

 tissues. Small doses of filtered cultures injected into rodents 

 produce symptoms of paralysis and the other symptoms met 

 with in outbreaks ; larger doses are rapidly fatal. 



Organisms of the Gaertner group. 



Modern investigation has shown that when outbreaks of 

 food poisoning are bacteriologically investigated, in the majority 

 of cases members of the Gaertner group of bacilli are isolated 

 and can be shown to be the cause of the outbreak. These 

 bacilli are now recognized as by far the most important cause of 

 bacterial food poisoning. The members of this group stand in 

 their cultural characters between the chemically active B. coli 

 group and the chemically rather inactive typhoid group. They 

 may be divided into two subgroups, (a) true Gaertner bacilli, 

 (b) para-Gaertner bacilli. The para-Gaertner bacilli are a number 

 of organisms, for the most part unnamed, which appear to be not 

 uncommon in the healthy animal and human intestine. They 

 are for the most part non-pathogenic and are also differentiated 

 from the true Gaertner bacilli by failing to be agglutinated by 

 the anti-sera of members of the true group, and by certain 

 fermentative properties. Many for example fail to ferment 

 dulcite or actively ferment salicin. 



The true Gaertner group bacilli are culturally indistinguish- 

 able, but can be differentiated by means of agglutination and 

 other serological and immunity tests into at least three organ- 

 isms, i.e. B. enteritidis, B. suipestifer and B. paratyphosus /?. 



There is still some controversy as to the question whether 

 the last two organisms are identical or not, the prevailing 

 German view being that they are identical, while English in- 

 vestigators, for the most part, have found differences. 



In outbreaks of food poisoning B. enteritidis or B. suipestifer 

 is found, while B. paratyphosus /3 is found in cases of paratyphoid 

 fever. 



The two former bacilli are also met with in connection with 



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