106 AGGLUTINATION. 



4. Dysentery. The agglutination property is employed both for testing 

 the serum, and identifying cultures. The Flexner type of bacillus, produces 

 agglutinins more readily than that of Shiga-Kruse. They are also agglu- 

 tinated more readily. Only positive reactions in dilutions of i : 30, are of 

 diagnostic consideration. Occasionally partial agglutination takes place 

 with heterologous dysentery strains, typhoid and colon bacteria. 



5. Pest. The reaction is very specific, but of slight significance, as it appears only 

 upon the ninth day; occurring with a serum dilution of i : 3, it is considered of positive 

 diagnostic value. 



6. Malta Fever. In most instances the serum gives the agglutination reaction with the 

 micrococcus melitensis. Normal serum may give the reaction in dilution i : 30, so 

 that higher dilutions only are of aid in diagnosis. 



7. Staphylo, Strepto and Pneumococci. Clinically, the agglutination test is never 

 employed in these cases. 



8. Tuberculosis. Here the agglutination test is associated with the difficulty of obtain 

 ing a homogeneous tubercle bacillus suspension. This, however, is overcome by one of 

 two ways. 



a. Arloing-Courmont's Method (1898). The tubercle bacilli are obtained in the so- 

 called "homogeneous culture" form. S. Arloing first grows the bacteria upon potatoes for 

 a long time, and then transplants them into glycerin bouillon which is agitated, daily for 

 five minutes. After a number of subcultivations, a culture is finally obtained after several 

 months. This grows rapidly in a few days and diffusely clouds the broth. 



Such a culture diluted with physiological saline solution, is used for the test. Here 

 small test-tubes are preferable and the ingredients should be mixed after the following 

 proportions : 



2 drops of serum + 10 drops of culture (i : 5) 

 i drop of serum + 10 drops of culture (i : 10) 

 i drop of serum + 15 drops of culture (i : 15) 

 etc. 



The combined substances are well shaken and placed into an incubator. According to 

 Arloing and Courmont, a positive reaction even in the dilution of i : 5 speaks for tuber- 

 culosis. Best results are by this means obtained in incipient and mild tubercular cases; 

 those which are farther advanced do not react. 



b. Method of Koch. Koch filters the ordinary tubercle bacillus bouillon cultures, dries 

 the remnants upon the filter, and rubs them up in an agate mortar with N/5o NaOH 

 up to a dilution of i : 100. The solution is centrifugalized and enough weak HC1 is 

 added until the reaction is only slightly alkaline. The dilution is then brought up to i : 

 3000 by the addition of 0.5 per cent, phenol in normal saline, and kept for twenty-four 

 hours in the incubator. 



A somewhat simpler procedure is to dilute new tuberculin B. E. to i : 100 with 0.5 

 per cent, of carbolic saline solution, centrifugalize this for six minutes and then dilute to 

 i : 1000. The solution thus obtained can be preserved in the ice-box for fourteen days. 

 Just before using, a still further dilution of i : 10 is made. 



The agglutination test has not been generally adopted as a method for diagnosis. 

 The technique is rather difficult, and the results not absolutely reliable. The reason for 

 the latter is that high agglutination values are rarely met with, and slight ones are found 

 even in normal individuals. Then, too, the methods of tuberculin diagnosis are so much 

 simpler, that they have been given the preference. 



