10
MASTITIS ORGANISMS
[Vol. XXVIII, Part II,
The milk samples collected 24 hours after the administration of treatment
were bright yellow in colour and clotted. No apparent inflammatory changes or
oedema was observed, nor any of the samples were bloody. The secretion returned to
normal, generally after two to four days.
To tudy the antibiotic levels in the post-treatment milk after 24 hours, the
milk as such and its serial doubling dilutions were inoculated with organisms 5F,
8F and B. coil whose in vitro sensitivity to the antibiotic had been predetermined.
It was observed that Str. pyogenes 5F and Staph. aureus 8F could grow in whole
milk. B. coil did not grow in 50 per cent dilution but was resistant to 25 per cent
concentration of the milk in serum broth. The results are suggestive that anti
biotic levels in 24 hours post-treatment milk are 0.015-5 and below.
The milk samples collected 24 hours after the infusion of the first tube were
generally found to be sterile except 5F which gave few β haemolytic colonies
after 48 hours of incubation. The quarter remained a shedder and the leucocyte
count was 5,000,000 one week and 5,500,000 one month after the treatment. Flakes
were always present, the quarter gradually got indurated and the secretion stopped
when the cow ultimatly dried up.
Quarter 42/1 infected with Str. uberis also did not respond to treatment. The
organisms were isolated one month after the treatment and the leucocyte count
went up to 75,000,000 per ml. of milk. The quarter got indurated and the milk
yield decreased appreciably.
All the quarters shedding coagulase positive β haemolytic Staph. aureus were in
preclinical or clinical stage of mastitis and showed uneventful recovery. The post-
treatment milk samples were found to be sterile and the milk generally returned to
normal a week after the treatment.
Quarter 4F had shown an acute inflammatory condition and was constantly kept
under observation. The pretreatment milk contained flakes. The microscopic
examination revealed fibrin and a leucocyte count of 3,000,000. After 24 hours of
treatment the fresh and the incubated milk did not give any growth on blood agar
after 24 and 48 hours of incubation at 37°C. Six days after the treatment the leu
cocyte count was 4,000,000 and fibrin was present. Culturally it was sterile. The
leucocyte count was 1,130,000 after 10 days and 300,000 after 14 days when the
milk became thin and watery in consistency, flakes disappeared and no fibrin could
be detected on microscopic examination. It was after a month that consistency of
the milk returned to normal, leucocyte count became 100,000 per ml. of milk and
the quarter mainfested a clinical cure.
Eight quarters shedding non-haemolytic Staph. albus and giving a high leuco
cyte count accompanied with other chemical changes in the milk due to inflammatory
process showed a favourable response to the treatment. The number of leucocytes
per ml. of milk showed a significant decrease and all the milk samples were found
to be culturally sterile one month after the treatment. One case of E. coli infection
included in the experiment showed clinical cure and the milk was culturally sterile
a week after the treatment. Non-pathogenic Str. lactis was also successfully elimi
nated from the treated quarter.