44
Streptococci from Equine Strangles in India
confirming the utility of lactose, trehalose
and sorbitol as differential substances,
they have shown that colony characteristics
and slide agglutination tests are useful
adjuncts for type differentiation. Five
types of equine streptococci were found
by them and the distribution of these
types in various infections was indicated.
MATERIAL AND METHODS
Of the 39 strains studied 11 were receiv
ed from Major W.P.S. Edwards, R. A. V. C.,
who had isolated them from strangles
abscesses in India. Six strains were isola
ted by us from material obtained by
Srinivasan and Choudhury (article in
press) at Mukteswar, viz. from deep
swabs from the nostrils and from pus
of fresh submaxillary abscesses. Two
strains were isolated by Mr Shirlaw from
orchitis in donkeys. Ten strains, repre
senting types 1, 2, 3, and 4 of Bazeley. and
Battle [1940], were received in a dried
state from Mr Bazeley of the Common
wealth Serum Laboratories, Australia.
They had been isolated from fresh or
previously opened strangles abscesses and
from respiratory catarrh. Ten were our
own laboratory strains from cases of
strangles. A few of the strains mention
ed above were from sources other than
strangles but they were included in order
to determine their type.
With all materials purity tests were
first made on blood agar and represen
tative colonies identified by biochemical
tests. Stock cultures were kept on blood
agar slants under paraffin. Haemolysis
tests were made on 5 per cent sheep-blood
agar, observations being made before and
after refrigeration. Fermentation tests
were made in peptone water containing
1 per cent horse serum and Andrade indi
cator, 1 per cent of the 'Sugar' being added
from an autoclaved solution. Incubation
was for seven days and seeding was heavy
from an actively growing culture. The
final pH in 1 per cent glucose broth [Avery
and Cullen, 1919] was made after three
days. The methylene blue reduction test
was made much according to the technique
of Edwards [1933], the medium being
beef infusion containing 10 per cent casein
digest, 1 per cent peptone and medicinal
methylene blue to give final concentration
of 1 : 100,000. The medium was seeded
from an actively growing culture and
examined after 24 hours at 37° C. Growth
in bile salt was tested according to
Belenky and Popowa [1929], viz. on blood
agar plates containing 10 and 40 per cent
sodium taurocholate. Hydrolysis of so
dium hippurate was tested by the method
of Ayers and Rupp [1922].
Serological Group differentiation by
precipitation tests was made according
to Lancefield [1928] and type differenti
ation by slide agglutination tests according
to Bazeley and Battle (loc. cit.) Sera were
from rabbits which had received at five
day intervals eight injections of carefully
heat-killed young streptococcus culture, as
advised by Bazeley and Battle.
Suspensions for agglutination tested
were made as follows: Overnight culturel
in tryptic digest broth, containing varying
quantities of horse serum up to 5 per cent
were centrifuged and the deposit suspended
in saline with 1: 10,000 merthiolate. Sera
unabsorbed and absorbed with heterologous
strains, were diluted to give specific agglu
tination in 20 seconds. Equal-sized drop
of serum dilution and suspension were
placed side by side within 1 in. squares of
glass plates, run together, rocked and the
time for agglutination noted.
RESULTS
All strains belonged to Lancefield
group C, were β-haemolytic, and not hea
resistant (60°C. 30 min.). The classification
adopted was that used by Bazeley and
Battle (loc. cit). Differentiation was main
by biochemical tests, for in slide agglut
nation tests, cross reactions were obtaine
between the types, even with the use
absorbed sero and sera diluted to end titr
Most new strains could be assigned to on
or other of Bazeley's biochemical typs
2 and 4 (Table I). Type 1 strains (S
equi) differ from others by their inability