Feb. 7,1916 
Agglutination Test for Bacterium abortus 
875 
While, in Tables I to IV, a positive agglutination test points to the 
presence of BacL abortus in the milk, this is not always true if judged by 
guinea-pig inoculation. In several cases the writer was unable to get 
positive lesions in guinea pigs with milk from all four quarters that gave 
a positive agglutination reaction. In these instances it is probable that 
the agglutinins were coming from the blood stream, or, if due to a bacte¬ 
rial invasion of the udder, the bacterium may have been present in too 
small numbers to cause lesions in guinea pigs with the 5 c. c. of milk used 
for inoculation. In the instances of agglutination with negative guinea- 
pig inoculation it was noticed that the reaction from quarter to quarter 
seemed to be fairly constant. In the tables given, the reaction is seen to 
vary a good deal from quarter to quarter. This, the writer believes, 
indicated that in the cases of reaction without pathogenicity to guinea 
pigs the agglutinins Tyere coming to each quarter from a common source 
the blood. 
Though many samples of milk have been inoculated into guinea pigs, at 
no time has a sample been found with a negative agglutination test that 
would produce the typical lesions of infectious abortion. 
The present value of this test is that it enables one to select from a herd 
the cows whose udders may be infected with Boot . abortus . The com¬ 
paratively small number separated by this method may then be examined 
by guinea-pig inoculation and cultural methods. 
If Bact. abortus is found to be pathogenic for humans, as has been 
suggested by Melvin, 1 this test may be of value as another means of 
safeguarding certified and all unpasteurized milk. 
From observations and tests now being made it appears that it may be 
possible to differentiate samples in which the agglutinins come from the 
blood from those in which the agglutinins are produced in the udder. 
SUMMARY. 
A pure culture of Bacterium abortus Bang introduced into the milk 
cistern of a cow's udder caused the appearance of agglutinins in the milk. 
In every case in which Bact. abortus was found present in the milk by 
animal inoculation the agglutinins for this organism were also found, but 
this bacterium was not found in every case in which agglutinins were 
demonstrated. 
The agglutination test is of value in studying the presence of BacL 
abortus in milk when it is desired to study a large number of samples. 
If BacL abortus is found to be pathogenic for humans, this test may be 
of value as another means of safeguarding certified and all unpasteurized 
milk. 
1 Melvin, A. D. Infectious abortion of cattle and the occurrence of its bacterium in milk. I.—Introduc¬ 
tory statement. In U. S. Dept. Agr. Bur. Anitn. Indus. 28th Ann. Rpt. 1911, p. 137-138. 1913- 
