ORIGINAL ARTICLES
BACTERIOLOGY OF BOVINE MASTITIS IN INDIA WITH SPECIAL REFER-
ENCE TO THE INCIDENCE OF STREPTOCOCCUS AGALACTIAE
By RAM NARAIN MOHAN, Imperial Veterinary Research Institute, Izatnagar
(Received for publication on 26 April 1945)
VETERINARY clinicians in India have been quite
familiar with mastitis as an affection of milch cattle,
but it was not until the beginning of the last decade
that the subject received serious consideration.
The investigations of various workers in Europe
and North America supplied the much needed
stimulus in this direction, so that from 1935 the
subject has been given more attention than before.
In this paper is given a consolidated summary of
the work done from 1935 to 1942. This includes
a systematic survey of the incidence of Streptococcus
agalactiae infection in some dairy herds. The main
object has been to obtain some preliminary
knowledge of the bacteriology of bovine mastitis
in India. The work was started primarily to deter-
mine the common bacterial types associated with
it, and secondly, the extent to which Str. agalactiae,
the most important and common cause of chronic
streptococcus mastitis in other countries, is respon-
sible for udder infections in this country.
The. observations made are described under two
sections I and II.
SECTION I
Under this head is described the preliminary
work done from 1935 to 1940 to determine the types
of bacteria associated with mastitis, and especially
to see if Str. agalactiae could be commonly isolated.
MATERIAL AND METHODS
The material examined came, as a rule, from cows
and buffaloes affected with clinical mastitis in the
experimental dairy herds at Mukteswar or from
different parts of the country. In the case of the
Mukteswar cows, the material consisted of mixed
udder milk or more commonly milk from affected
quarters. The technique adopted was to streak the
centrifuge deposit on blood or plain-agar slants
for primary isolation of bacterial types. In many
cases, cultures were obtained with a fair degree
of purity. The material received from the field
was generally milk or a more or less purulent udder
secretion, swabs of milk or pus, and in one case a
portion of the affected mammary gland preserved
in glycerine. The cultural technique adopted with
these specimens was similar to that used for milk
from the Mukteswar cows. In many cases films
of the udder secretion or milk deposit were also
examined for bacteria and pus-cells. Many of the
Mukteswar cows and a couple of ' field ' cows were
reexamined.
The bacteria isolated in pure culture and suspected
of being connected with the disease were studied.
In the early stages of the work, the system of classi-
fication recommended by Bergey was used. This
largely explains why Str. agalactiae, though probably
present, was not definitely identified until 1939,
after which it became the general practice to submit
all the streptococcus strains to the biochemical
tests now recommended for classifying mastitis
streptococci.
RESULTS
Only the more important features are given below.
1. Streptococci. About 55 strains of streptococci
were recovered from 45 animals (18 Mukteswar
and 27 ' field' animals). Few of these strains
were subjected to a thorough examination, so that
the identifications recorded would not satisfy modern
standards. The more definite and reliable specific
labels are considered below.
(a) Str. agalactiae. Str. agalactiae was isolated
from ten cows and one buffalo ; seven of these were
' field ' cows. This number also includes one Str.
mitior strain which on later examination proved to be
Str. agalactiae. At least one other strain, which
had been considered to belong to ' Mastitis Strepto-
coccus, Group I ' (Minett, Stableforth and Edwards)
may have been a true Str. agalactiae. but it was not
available for further examination.
(b) Str. mitior. Str. mitior was isolated from three
cows, two of which were ' field ' cases, and one
buffalo. Perhaps all, and certainly one of these
strains should be regarded as Str. agalactiae. The
buffalo strain was not available for further exami-
nation, but the animal itself was two years later
found to be infected with Str. agalactiae.
(c) Str. uberis. Str. uberis was said to have been
isolated from two ' field ' cows, but the diagnosis
was based on incomplete study. Organisms labelled
'haemolytic
diphtheroids ', probably Corynebac-
terium pyogenes, were also recovered from these
cows.
(d) Str. subacidus. The characters of this orga-
nism are fully described in Section II. Strains of
streptococci possessing such characters were re-
covered repeatedly from two Mukteswar cows.
During the later survey work, one of these proved
173