Objective—To determine sources and amounts of
variation in a kinetics ELISA (KELA) and results of culture
of fecal samples for Mycobacterium avium subsp
paratuberculosis (MAP) in repeated tests of individual
Animals—112 cows on 6 commercial dairy farms in
Procedure—A nonrandom longitudinal study was
conducted from January 2001 to March 2002. A KELA
was performed monthly, and MAP culture was performed
bimonthly. Cow- and herd-level data were collected.
The KELA and culture results were analyzed by
use of models that corrected for clustering within
herds and repeated measures on cows.
Results—Cows of second or higher lactation had
increased KELA values, compared with values for
first-lactation cows. Cows had lowest KELA values
during the first 15 days in milk; KELA values increased
until 60 days in milk and then stabilized. Moderate
and heavy shedders had significantly higher KELA values
than culture-negative cows, and KELA values of
shedders progressively increased over time. On average,
the KELA value was significantly increased 132
days after a cow was first detected to be a moderate
shedder and 236 days after a cow was first detected
to be a low shedder.
Conclusions and Clinical Relevance—Analysis suggests
that KELA results vary on a cow-level on the
basis of lactation number and stage of lactation. High
KELA values indicate heavy fecal shedding, but the
KELA is not useful in identifying low and moderate
shedders that can require up to 236 days to have a
significant increase in KELA value. (Am J Vet Res
Objective—To determine the effect of nonthermal plasma on Staphylococcus aureus, fibroblasts in monolayer culture, and clean and contaminated skin explants.
Sample Population—Normal skin from euthanized horses.
Procedures—S aureus organisms were plated and treated with nonthermal plasma followed by bacterial culture to assess viability. Fibroblasts in monolayer culture and the epidermal and dermal surfaces of clean and S aureus–contaminated skin explants were treated. The effects of distance and duration on the response to treatment were compared.
Results—Compared with controls, treatment with nonthermal plasma resulted in significantly decreased bacterial growth and significantly inhibited survival of fibroblasts in monolayer culture. When epidermal and dermal surfaces of skin explants were treated, there was no effect on production of normal fibroblasts during explant culture, except when extended exposure times of ≥ 2 minutes were used. Treatment with nonthermal plasma resulted in significantly lower bacterial counts after 24 hours of culture of S aureus–contaminated epidermis but not of dermis.
Conclusions and Clinical Relevance—Nonthermal plasma resulted in bacterial decontamination of agar and epithelium; negative effects on fibroblasts in monolayer; and no negative effects on skin explants, except at long exposure times. Use of nonthermal plasma appears safe for treatment of epithelialized surfaces, may be safe for granulating wounds, and results in decontamination of S aureus. Investigations on the effects that nonthermal plasma may have on patient tissues are indicated with a clinically applicable delivery device.
Objective—To evaluate sensitivity of microbial culture
of pooled fecal samples for detection of
Mycobacterium avium subsp paratuberculosis (MAP)
in large dairy herds and assess the use of the method
for estimation of MAP prevalence.
Animals—1,740 lactating cows from 29 dairy herds
Procedure—Serum from each cow was tested by
use of a commercial ELISA kit. Individual fecal samples
were cultured and used to create pooled fecal
samples (10 randomly selected fecal samples/pool; 6
pooled samples/herd). Sensitivity of MAP detection
was compared between Herrold's egg yolk (HEY) agar
and a new liquid culture method. Bayesian methods
were used to estimate true prevalence of MAP-infected
cows and herd sensitivity.
Results—Estimated sensitivity for pooled fecal
samples among all herds was 0.69 (25 culture-positive
pools/36 pools that were MAP positive).
Sensitivity increased as the number of culture-positive
samples in a pool increased. The HEY agar
method detected more infected cows than the liquid
culture method but had lower sensitivity for
pooled fecal samples. Prevalence of MAP-infected
cows was estimated to be 4% (95% probability
interval, 2% to 6%) on the basis of culture of
pooled fecal samples. Herd-level sensitivity estimate
ranged from 90% to 100% and was dependent
on prevalence in the population and the sensitivity
for culture of pooled fecal samples.
Conclusions and Clinical Relevance—Use of pooled
fecal samples from 10 cows was a cost-effective tool
for herd screening and may provide a good estimate
of the percentage of MAP-infected cows in dairy
herds with a low prevalence of MAP. (Am J Vet Res