ABSORPTION OF AGGLUTININS 389 



[Co-agglutinins in the serums of enteric patients.] 



[In addition to the specific, homologous or primary agglutinins for the 

 typhoid bacillus, the serum of enteric fever patients often contains group or 

 heterologous or secondary agglutinins for bacilli of the paratyphoid and 

 salmonella groups. 



[In a consecutive series of 86 serums Boycott found that 59 per cent, con- 

 tained secondary agglutinins and of this series 55 per cent, reacted with 

 B. Gaertner and Paratyphosus A (Brion and Kayser), 41 per cent, with Para- 

 typhosus B (Schottmiiller), 33 per cent, with Aertrycke and 12 per cent, with 

 Paratyphosus B (Schottmiiller). Generally speaking the more typhoid 

 agglutinin there is present, the more secondary agglutination is likely to 

 be found.] 



The application of the serum test to the identification of the 

 typhoid bacillus. 



The application of the agglutination reaction to the identification of the 

 typhoid bacillus may be of considerable service but is not a test sufficiently 

 delicate and specific to determine the identity of the bacillus with certainty. 



For the purpose of testing whether a given organism be the typhoid bacillus 

 or no it is better to use the serum of a person suffering from the disease which 

 agglutinates quite distinctly in a dilution of 1 in 100 than an artificially 

 prepared anti-typhoid serum. 1 Typical typhoid bacilli are agglutinated by 

 this serum in dilutions varying from 1 in 50 to 1 in 100. Strains of the 

 colon bacillus on the other hand are never agglutinated, or at most only in 

 dilutions of 1 in 5 to 1 in 10. A postulate such as the following would render 

 the diagnosis very simple : any bacillus agglutinated in a dilution of 1 in 50 

 may be legitimately described as a typhoid bacillus. 



Unfortunately, it is now established that there are some undoubted typhoid 

 bacilli which are not agglutinated by the serum of a person suffering from 

 enteric fever. Remy has shown that a typhoid bacillus which agglutinated 

 well at first readily lost this property when grown symbiotically with the colon 

 bacillus for a few weeks. Occasionally, strains of the typhoid bacillus isolated 

 from the living body or from water can be agglutinated only with difficulty, 

 and it is not until they have been sub -cultivated a certain number of times 

 on artificial culture media that agglutination capacity is acquired (Courmont, 

 Chantemesse, Remy, Sacquepee and others). When a suspected typhoid 

 bacillus has failed to give the serum reaction the following experiment may 

 be carried out with the object of identifying the organism. Inoculate a 

 guinea-pig every other day for a fortnight with 2 c.c. of a forty-eight-hour 

 broth culture of the bacillus under investigation. If the blood of the guinea- 

 pig now agglutinates an undoubted typhoid bacillus in a minimum dilution 

 of 1 in 40 the organism which served for the inoculation of the animal may 

 be regarded as a true typhoid bacillus. Some strains of undoubted typhoid 

 bacilli however escape even this method of recognition (Remy). 



8. Absorption of agglutinins. 



Castellani's absorption or saturation method can also be applied to the 

 differentiation of the typhoid bacillus from closely allied organisms and by 



1 In the case of animals highly immunized against the typhoid bacillus, Rodet has 

 shown that the blood not only agglutinates the typhoid bacillus in very high dilutions, 

 but that it also has marked agglutinating properties for some strains of the colon bacillus. 

 Pfaundler, Bruns, Kayser, have shown that very highly immunized serums agglutinate 

 not only the organism against which the animals were immunized but also closely related 

 species. 



