Objective—To determine patterns of mycoplasma
shedding in the milk of dairy cows with intramammary
Design—Prospective clinical trial.
Animals—10 Holstein cows with intramammary
Procedure—Milk samples were collected from each
cow daily for 28 days and plated on mycoplasma agar
to evaluate shedding patterns. To determine whether
enrichment improved recovery of organisms, some
samples were also inoculated in mycoplasma enrichment
medium and incubated for 4 days prior to plating.
Somatic cell count (SCC) was determined in samples
Results—Mycoplasma organisms were not isolated
from 81 of 280 (29%) composite milk samples, but
> 106 colonies/mL were obtained from 151 (54%).
Similarly, mycoplasma organisms were not isolated
from 433 of 1,008 (43%) quarter milk samples, but
> 106 colonies/mL were obtained from 392 (39%). For
71 of 104 (68%) samples, mycoplasma organisms
were isolated both following direct plating and following
enrichment; for 24 of 104 (23%), mycoplasma
organisms were isolated only following enrichment;
and for 9 of 104 (9%), mycoplasma organisms were
isolated only after direct plating. There was a linear
correlation between logarithm of the SCC and logarithm
of the number of colony-forming units of
mycoplasma per milliliter of milk for composite and
quarter milk samples.
Conclusions and Clinical Relevance—Shedding of
organisms was inconsistent in dairy cows with intramammary
mycoplasma infection, increasing the risk
of misdiagnosis if multiple milk samples are not tested.
(J Am Vet Med Assoc 2003;223:1163–1166).
Objective—To determine the epidemiologic pattern of
intramammary infections (IMIs) with Staphylococcus
aureus during implementation of a control program in
9 commercial dairy herds.
Animals—1,651 lactating cows and 53,098 quarter
Procedures—Nine herds located in different regions
of Italy were enrolled. Control of S aureus infections
followed the general principles of contagious mastitis
control and was based on precise diagnostic procedures
and strict control and segregation of infected
cows. All lactating cows in each herd were tested,
and those free of S aureus IMI were enrolled as the
cohorts. Further additions to the cohort group were
cows and heifers free of S aureus IMI, as determined
from aseptically collected milk samples taken approximately
7 and 14 days after calving.
Results—After the ninth month of the program, incidence
decreased to < 2 new IMIs/100 cow-months in
7 of the herds. At the end of the study, 8 of 9 herds
had an incidence of ≤ 1 new IMI/100 cow-months.
Heifers were most at risk of developing an IMI.
Conclusions and Clinical Relevance—Results suggest
that control of S aureus IMIs can be achieved by
use of a control program based on segregation and
use of hygienic and therapeutic protocols. Analysis of
incidence and identification of risk factors in a herd
could avoid the possible shortcomings of the program,
maximizing the probability of success. (J Am
Vet Med Assoc 2003;223:684–688)
Objective—To determine whether Mycoplasma
strains typically associated with mastitis in dairy cattle
can be isolated from body sites other than the
Design—Prospective clinical trial.
Animals—7 Holstein cows in various stages of lactation
with intramammary Mycoplasma infection.
Procedure—Milk samples, antemortem swab specimens
from various body sites, and postmortem swab
and tissue specimens were submitted for Mycoplasma
culture. Pulsed-field gel electrophoresis (PFGE) was
performed on chromosomal digests of all Mycoplasma
isolates. Isolates with the same number and size of
chromosomal digest bands were considered to be of
the same type.
Results—For each cow, all isolates obtained from
milk, mammary gland parenchyma, and supramammary
lymph nodes had the same PFGE pattern. All
cows had at least 1 isolate from nonmammary system
tissues that had the same PFGE pattern as isolates
from the mammary system. Overall, 44 of the
70 (63%) Mycoplasma isolates obtained from body
sites other than mammary system sites had the
same PFGE pattern as did mammary system isolates.
Conclusions and Clinical Relevance—Results confirmed
our hypothesis that Mycoplasma strains isolated
from the milk of dairy cattle with Mycoplasma
mastitis frequently have PFGE patterns identical to
those for strains isolated from other body sites, suggesting
that there is at least a potential for internal
transmission of Mycoplasma organisms. (J Am Vet
Med Assoc 2005;227:455–459)