INDIAN SPECIES OF BRUCELLA
By J. B. POLDING, Indian Veterinary Research Institute, Mukteswar-Kumaon
(Received for publication on 8 May 1947)
N OT all Brucella can be exactly classified and in an examination of some 2,000 strains Huddleson
[1939] refers to 13 that were not precisely abortus, melitensis or suis. Huddleson has recently
intimated to me that a correspondent of his has encountered a certain atypical variant in Indonesia,
which appears to be indigenous to that country. The characteristics therefore of strains isolated
in India will be of interest and in this paper are described some 49 strains collected at random from
this country.
EXPERIMENTAL
Methods
The criteria used for typing were, (1) CO 2 requirements at time of isolation, (2) H 2 S secretion,
(3) inhibitory action of dye media, and (4) antigenic structure. The techniques of items (1) to (3)
were those of Huddleson [1939], that of (4) was based on the work of Wilson and Miles [1932]. Controls
with type-specific strains were prepared throughout.
Strains were examined for dissociation as follows. Two-day-old agar cultures were suspended
in 12 per cent. saline and adjusted to density 1 to 2 on Brown's scale. The suspensions were immersed
in boiling water and readings for agglutination made after 5, 15, 30 and 60 minutes. The suspensions
were then removed and left on the bench until the following morning when they were again examined
for agglutination. A strain agglutinating in these circumstances was regarded as dissociated.
Tests for antigenic sensitivity were made as follows. Standard antigens were prepared by
suspending 48-hour-old slant cultures in 12 per cent. saline and their density very accurately adjusted
to 1 on Brown's scale. Stableforth's [1936] standard dried serum was reconstructed according to
his directions, but the concentration of his final dilution series was halved in saline. In a series
of tubes, 0.5 c.c. of the antigen to be examined was added to 0.5 c.c. of each dilution of serum in the
halved Stableforth series, thus forming a titration range of 1/640, 1/800, 1/960 and 1/1120 and 1/1280
and the ultimate reaction after 24 hours' incubation at 37°C. was noted. In this range, type-specific
antigen prepared in a similar way had been previously found to react to about +
+
at 1/1280, and
this titre was accepted as the datum with which the end points of the titrations of the field strain
were compared.
Strain typing
In the intemperate climate of India, the procuring of satisfactory specimens for bacteriological
examination offers many peculiar difficulties. The main troubles are the early putrefaction of dead
tissues, dust contamination, long periods of transportation in warm environment and above all
difficulties of communication, for abortions usually occur without notice in remote localities, which
cannot be reached in time by persons qualified and equipped to take samples fit for examination. The
Brucella strains it has been possible to secure have thus been disappointingly few, but such as they
are their origin and classification are given in Table I.
In this classification, all 26 Br. abortus strains fell precisely into class, with no discrepancies.
It is also noteworthy that all came from organized farms, most of which have carried or are still
carrying European cross-bred stock, and that they occurred equally in cows and buffaloes. As
regards the melitensis strains, in all three there was little doubt as to their classification (Table II).
It will be observed that first two strains were rough, so that their antigenic structure could not
be examined, but in all probability they are normal melitensis types. They are alleged to have been
isolated some years ago from a cow and a goat in the Punjab. The third strain was isolated recently
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