272
Effect of Penicillin Injections on Staphylococci
[XVII
arrangements for the study so the penicillin was stored in a refrigerator until its use nine months
later, at which time, the assay value was 190 Oxford units per milligram. The contents of a single
vial was dissolved in 500 c.c. of sterile normal saline solution and injected in 1 dose. Each dose,
therefore, contained 22,800 Oxford units of penicillin. The solution was prepared immediately
before injection, the vials being stored in a refrigerator until that time.
TABLE III
Results of examination for staphylococci of milk samples from udder quarters receiving eight injections
intervals of six hours
Sample
Before injection—
1 . . . .
After injection—
2 . . . .
3 . . . .
4 . . . .
5 . . . .
6 . . . .
7 . . . .
8 . . . .
9 . . . .
Cow 91 L. H. Quarter
Staphylococci
Poured
Plate
H
—
—
—
—
—
—
—
—
Steaked
Plate
H
—
—
—
—
—
—
—
—
Coagu-
lation
—
Cow 10 L. F. Quarter
Staphylococci
Poured
Plate
H
—
—
—
—
—
—
—
—
Steaked
Plate
H
—
—
—
—
—
H
NH
NH
Coagu-
lation
+
+
—
—
Cow 10 R. H. Quarter
Staphylococci
Poured
Plate
H
—
—
—
—
H
H
H
H
Steaked
Plate
H
—
—
—
—
—
H
H
H
H
Coagu-
lation
+
+
+
+
+
Cow 1 R .H. Quarter
Staphylococci
Poured
Plato
NH
—
—
—
—
—
NH
—
—
—
Steaked
Plate
NH
—
—
—
—
NH
NH
NH
NH
Coagu-
lation
+
—
—
—
—
Ox-blood agar plates: H=hemolytic colonics; NH=nonhemolytic colonics;— = no staphylococci colonies; +=coagulation; —=no
coagulation.
Four of the quarters selected for treatment were given 8 injections of 500 c.c. of the solution,
via. the teat canal, at intervals of six hours, and three received 4 injections, at 12 hour intervals.
The treatment was begun at the time of the regular evening milking. Just before the cow was
milked, a sample of milk was taken in the manner described previously, from the quarter to be
injected. After the cow was milked by the regular milker, the quarter was stripped; the teat wiped
with 70 per cent alcohol; and the first injection made. These samples were given the designation 1,
and the containers were marked with this number and the number of the cow. The quarter was
also indicated. Before each subsequent injection, the quarter to be injected was milked out as
thoroughly as possible. Samples were taken every 12 hours from both groups of quarters, i.e.
from those receiving 8 injections and those receiving 4 injections. All cows in the experiment were
milked before any of the other cows in herd.
The schedule followed in making the injections and taking the milk samples for laboratory
examination is presented in Table I. Referring to this Table, it will be seen that the samples taken
from the quarters receiving 8 injections and numbered 2, 3, 4 and 5 were drawn from the treated
quarters six hours after the last of 2 injections, given six hours apart, and that the samples from the
cows receiving four injections and numbered 2, 3, 4 and 5 were each taken 12 hours after a single
injection. Samples were also taken from both groups on the third, sixth, tenth, and thirteenth days
following the last injection and numbered 6, 7, 8 and. 9, respectively. These samples were taken
immediately before the evening milking. Each sample container was marked to indicate the number
of the sample, the number of the cow, and the quarter.