588 
Journal of Agricultural Research 
Vol. XXIX, No. 12 
COMPARISON OF CULTURAL AND 
ATMOSPHERIC REQUIREMENTS 
OF BACTERIUM ABORTUS (BO¬ 
VINE) WITH THOSE OF BAC¬ 
TERIUM MELITENSIS 
When the isolation of Bacterium 
melitensis through guinea-pig inocula¬ 
tions were being attempted, the writer 
was also testing the efficacy of abortion- 
bacterin treatment as a means of eli¬ 
minating Bad. abortus from udder- 
infected cows. Sixteen cows, all cases 
of natural infection, were being 
used in this experiment. Three or 
four guinea pigs were injected with 5 
c. c. quantities of milk from each cow 
at brief intervals and later destroyed, 
subjected to the agglutination test for 
abortion disease, and cultured with the 
object of determining whether any of 
the cows had ceased to be carriers of 
the microorganism or were still pro¬ 
ducing milk infected by Bad. abortus. 
On January 29, when guinea pigs 
Nos. 77497 and 77498 were destroyed 
and cultured, 43 guinea pigs previously 
inoculated with milk of the above- 
mentioned cows were also destroyed, 
autopsied, cultured, and subjected to 
the agglutination test for abortion dis¬ 
ease. Cultures were made from the 
spleens of all the animals, using for 
medium the lot of serum-agar slants 
employed for culturing guinea pigs No. 
77497 and 77498. Enough slants were 
inoculated with the spleen of each 
guinea pig to allow the incubation of a 
portion of the cultures under both CO 2 
and normal atmospheric conditions. 
The suspected Bacterium melitensis cul¬ 
tures were placed in the same jars con¬ 
taining 10 per cent C0 2 as the Bad. 
abortus cultures. In other words, cul¬ 
tural conditions were identical. 
Examination of the cultures incu¬ 
bated under normal atmospheric condi¬ 
tions on January 30 and January 31 
failed to reveal any evidence of growth. 
On February 1 the tubes subjected to 
both methods of incubation were 
examined. Serum-agar slants from 
spleen of guinea pig No. 77497 showed 
small opalescent colonies under both 
methods of cultivation. Likewise 
serum-agar slants from testicle and 
spleen of guinea pig No. 77498 showed 
small colonies under both conditions. 
There appeared to be little or no differ¬ 
ence in size of colonies under both 
methods of incubation. 
Thirty-five serum-agar slants from 
spleens of the abortion experiment 
guinea pigs incubated in closed jars with 
10 per cent C0 2 showed opalescent col¬ 
onies indicative of Bacterium abortus. 
The colonies were considerably larger 
than those suspected of being Bad. 
melitensis. Under normal atmospheric 
conditions a like number of tubes 
showed no evidence of growth, although 
sown with spleen tissue of these same 
guinea pigs. The cultures were fur¬ 
ther subjected to the same conditions 
of incubation, and on February 5 the 
colonies developing from inoculations of 
guinea pigs Nos. 77497 and 77498 on 
serum-agar slants had increased con¬ 
siderably in size. The tubes under the 
two methods of incubation differed but 
slightly, if at all. Colonies from the 
inoculations of these guinea pigs were 
visible on 3 percent glycerin-agar slants, 
and the infusion-bouillon cultures 
plainly showed evidence of rather lux¬ 
uriant growth. The colonies in the 
closed jars developing from the abor¬ 
tion experiment guinea pigs appeared 
considerably larger than those from the 
Bad. melitensis guinea pigs. Under 
normal atmospheric conditions the 
serum-agar slants from the abortion 
experiment guinea pigs appeared sterile 
and remained so until February 12, 
when they were discarded. 
While guinea pig No. 77497 showed 
well-marked lesions, the number of 
colonies developing from the spleen 
inoculations was less than 25 on any of 
the tubes of solid medium. Inocula¬ 
tions from the spleen of guinea pig No. 
77498 resulted in the isolation of from 
100 to 200 colonies each, although the 
lesions here were not pronounced. 
Antigens prepared from the infec¬ 
tions isolated from guinea pigs Nos. 
77497 and 77498 were agglutinated by 
Bacterium abortus and Bad. melitensis 
antiserums in such a manner as to indi¬ 
cate that either Bad. abortus or Bad , 
melitensis was being dealt with. 
Bacterium abortus was isolated from 
20 of the 43 guinea pigs employed in the 
abortion experiment when the cultures 
were incubated in a partial C0 2 atmos¬ 
phere. It is probable that numerous 
strains were represented, since in this 
test eight different cows used in the 
experiment were found to be still 
carrying the infection in their milk. 
Since numerous workers have ob¬ 
served that strains of Bad. abortus 
which have become accustomed to 
artificial media even after being in¬ 
jected into the bodies of bovines 
and multiplying for long periods can 
be readily cultivated again under 
normal atmospheric conditions, it may 
be well to state that no abortion 
vaccine had ever been used, nor arti¬ 
ficial infection of any animals with 
Bad. abortus practiced in the herd 
where the abortion experiment was 
being conducted. 
