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  • Author or Editor: Jeff D. Ondrak x
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Abstract

Objective—To evaluate effects of high incubation temperatures on results of protozoal culture and real-time PCR testing for Tritrichomonas foetus inoculated in a commercially available self-contained culture media system.

Design—In vitro experimental study.

Sample—2 strains of T foetus (1 field isolate from the University of California-Davis and 1 field isolate from the Texas Veterinary Medical Diagnostic Laboratory).

Procedures—2 sets of 36 dual-chamber media pouches were inoculated with T foetus (36 sample pouches/strain) and incubated at temperatures of 37.0°C (98.6°F), 46.1°C (115.0°F), or 54.4°C (130.0°F) for 1, 3, 6, or 24 hours. Six uninoculated media samples in pouches stored at 37.0°C for the entire treatment period were used as negative controls. Pouches were removed from incubators and stored at 22.2°C (72.0°F) until all treatments were complete. Samples were submitted to a diagnostic laboratory for protozoal culture and real-time PCR testing.

ResultsT foetus was detectable microscopically in inoculated pouches incubated at 37.0°C regardless of exposure time, whereas those incubated at 46.1°C yielded T foetus after 1 and 3 hours only, and those incubated at 54.4°C yielded T foetus after 1 hour only. Testing via real-time PCR assay yielded positive results for all inoculated media samples and negative results for all uninoculated control samples.

Conclusions and Clinical Relevance—Samples collected into the self-contained culture media system for T foetus testing via culture alone should be protected from high temperatures. Realtime PCR amplification may be a more reliable method for identification of the organism if storage and transport temperatures cannot be controlled.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare methods for identification of bulls that were carriers for Tritrichomonas foetus during an outbreak on a large beef ranch and determine whether the percentage of nonpregnant cows was associated with the percentage of bulls infected with T foetus.

Design—Epidemiological study.

Animals—121 Angus and Hereford bulls (1.5 to 6 years old) and 2,960 Angus-cross cows (2.5 to 14 years old) managed as 5 herds on a Nebraska beef ranch.

Procedures—3 sequential preputial scrapings collected from the bulls at 12- to 27-day intervals were cultured, and cultures were examined for live T foetus daily for 5 days. On day 5, aliquots of the culture fluid were tested by means of T foetus-specific gel and real-time PCR assays. Cows were tested for pregnancy by means of rectal palpation.

Results—For 361 preputial scrapings obtained from 121 bulls, results of culture and gel PCR assay were in close agreement. The real-time PCR assay had similar sensitivity to culture and the gel PCR assay but generated more false-positive results. Twenty-four of the 121 (19.8%) bulls were identified as infected with T foetus. For the 5 ranch herds, there was a positive linear correlation between percentage of infected bulls (range, 0% to 40%) and percentage of nonpregnant cows (range, 8.3% to 19.2%).

Conclusions and Clinical Relevance—Results suggested that a combination of culture and the gel PCR assay performed on 3 sequential preputial scrapings was the best method for identifying bulls that were carriers for T foetus during this herd outbreak.

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in Journal of the American Veterinary Medical Association
History

A 7-day-old 40-kg mixed-breed beef heifer calf was presented for recheck evaluation because of persistent signs of inspiratory dyspnea. Four days earlier, the calf had been examined because of labored breathing with marked abdominal effort that developed after the calf (unwitnessed birth) had been kicked and appeared rejected by its dam; was deemed to have had a clinically normal body temperature, pulse, and behavior and no obvious signs of dysmaturity or congenital defects; and then tube fed 2 L of colostrum harvested from its dam. During the initial examination 4 days earlier, the calf was febrile (rectal temperature unknown),

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in Journal of the American Veterinary Medical Association