AGGLUTINATION IN TYPHOID AND PARATYPHOID. 105 



artificial media and frequently subplanted. Possibly, the reason that the bacteria become 

 inagglutinable at all, is that they undergo immunization within the organism against the 

 existing agglutinins. By growing bacteria in agglutinating serum for a certain time, one 

 can obtain inagglutinable strains. 



i. Agglutinins for typhoid and paratyphoid A and B, can, not 



Agglutination infrequently, be demonstrated in the patient's serum as early 



in Typhoid as the third day, but as a rule, at about the beginning of the 



and Para- second week of the disease. Moreover, they remain within 



typhoid. tne serum for several weeks after the illness and disappear 

 only gradually. A positive agglutination test does not, how- 

 ever, mean the existence of the corresponding disease. A healthy bacillus 

 carrier can also have an agglutinating serum. Some cases of icterus catarrhalis 

 even give a positive Widal test. But in order to assign to this last a correct 

 explanation, one must remember that typhoid bacilli may remain in the gall- 

 bladder for years and thus lead to catarrhal inflammation and stone formation. 



Partial agglutinins from coli infections must always be considered. 

 Some authorities mention a positive Widal, in connection with endocarditis 

 maligna, sepsis, malaria, phthisis, and miliary tuberculosis. 



An absence of the agglutination test, especially at an early part of the 

 illness, should not influence a negative diagnosis of typhoid too greatly, 

 inasmuch as many cases are known where the reaction appeared for the 

 first time during the period of convalescence. In the employment of this test 

 as an aid for the differential diagnosis between several bacterial infections, 

 it is best to titrate the serum to its limit, as the higher titer for one class of 

 bacteria generally speaks in favor of the infection by the same. Para- 

 typhoid serum agglutinates typhoid bacilli only slightly, while true typhoid, 

 both typhoid and paratyphoid bacteria with equally high force. In severe 

 and difficult cases, Castellani's test should be performed. Paratyphoid 

 B. serum, always gives the limit of its agglutinating titer both with the 

 pathogenic mouse typhoid and hog cholera bacillus. 



2. Cholera. Only rarely has the agglutination test been employed with 

 the serum of patients thus afflicted. On the other hand, the identification 

 of cholera suspicious colonies in the stool is regularly conducted by means of 

 this test. For this purpose, it is very specific, as group reactions almost 

 never take place. Strongly agglutinating sera are easily obtained by immu- 

 nization of animals. 



3. Epidemic, Cerebrospinal Meningitis. Agglutination in this disease 

 serves mainly for the identification of suspicious meningococcus cultures. 

 As has been shown by Wassermann and Kutscher, some strains are agglu- 

 tinated only after a long period (twenty-four hours) and at higher tem- 

 peratures as 56 C.* 



* Frequently, during even the first days of the disease, the patient's serium in a dilution of 

 i-io gives the agglutination test. This is rare with higher dilutions of the serum as 1-50. It 

 usually takes some time before the agglutination becomes evident. 



