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- Author or Editor: Sang J. Shin x
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Abstract
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 cows.
Animals—112 cows on 6 commercial dairy farms in New York.
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 2003;64:479–484)
Abstract
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.
Abstract
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 in California.
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 2004;65:1061–1070)
