March, 1958]
S.
N.
BAKSHI
11
DISCUSSION
Generally speaking, the response of mastitic quarters to a therapeutic agent
depends on the species, the individual resistance of the responsible organism, the
capacity of the udder and the stage of disease. Representative and comparable
number of the diseased cases due to different aetiological organisms could not be
available during the period of study.
Although, all cases of Staphylococcal mastitis showed a very favourable res-
ponse to the treatment, it would be difficult to say on the basis of these results that
all types of cases due to this organism would give an equally good response. Deter-
mination of in vitro sensitivity of these organisms revealed that only 8F showed
comparatively enhanced resistance, but its in vivo response was quite satisfactory
and the organism was successfully eliminated from the quarter. Barnes [1955]
has reported that individual strains of Staph. aureus can resist a very wide range of
terramycin concentrations and Huebner [1956] has given a similar report about
their resistance to penicillin, bacitracin and erythromycin. Schalm [1950] observ-
ed that recovery from mastitis is not only related to duration of infection, and with
aureomycin he was able to cure a higher percentage of Staphylococcal mastitic
quarters of 7 to 48 months duration group than of less than 6 months group. This
further gives a support to the conception of individual variable resistance of Staphy-
lococci to treatment with any one of the antibiotics or their combination. Highly
resistant strains can always create a difficult position due to their refractivity to the
treatment. In the light of results obtained in this experiment it appears that udders
with an average milk yield of 10 to 15 lb. in the preclinical or clinical stage of disease,
due to Staphylococci sensitive to 0.03 mg. of oxytetracycline and 10 units of poly-
myxin or lesser concentrations per ml. of the combination of these antibiotics in
vitro, will respond satisfactorily to this treatment.
5F and 42/1 two cases due to Str. pyogenes and Str. uberis respectively were in
primary clinical stages with no palpable induration of the udders but they proved
to be quite resistant. Strains 5F also exhibited highest in virto and in vivo resis-
tance to the combination among the cases under report. Although 42/1 Str. uberis
exhibited in vitro sensitivity to the combination which was at a level with the other
strains of Streptococci yielding to the treatment, this organism proved to be more
resistant in vivo.
Two cases of mixed infection with Str. dysgalactiae and Staph. aureus, and Str.
agalactiae and Staph. aureus were treated successfully.
A special importance was attached to the leucocyte count in this study and it
was observed that once the infective organism was successfully eliminated, the fall
in the leucocyte count was a matter of course. Although, 4F showed a rise in the
leucocyte count a week after the treatment, gradually the number decreased and
about a month after the treatment it was within the normal range. The resistant
cases 5F and 42/1 did not show any fall; on the other hand, their was an increase
in the number which was significant in 42/1.
Very few references are available about the pathogenicity of Staph. albus for
the udder. Recently, Mukerji et al., [1956] have reported about their aetiological
significance for mastitis. Eight quarters shedding this organism and manifesting
inflammatory changes on chemical and microscopic examination were treated. The