Quick Detection of Contagious Equine Metritis

French researchers report they have developed a rapid, effective test for detecting the bacterium that causes the venereal disease contagious equine metritis (CEM). Taylorella equigenitalis is a Gram-negative bacterium that's responsible for CEM, which causes infertility and abortions in mares and infertility in stallions. Contagious equine metritis is considered a foreign animal disease in the United States, but it has afflicted horses here via imported stallions and semen.

According to the researchers, who work at the Laboratoire d'Etudes et de Recherches en Pathologie Equine, IPC, in Dozule, France, "The bacteria may be detected in equine genital swabs without need for a preliminary step of DNA extraction or bacterial isolation" in about four hours rather than the one to six days it takes for other types of testing.

According to Dr. Sandrine Petry, lead researcher on the study, bacterial isolation of T. equigenitalis can take four to six days. "In France, we must return a negative result only after six days of culture," she said. "And it's forbidden to make the bacterial isolation after 36 hours of swab realization." This means that the sample cannot be tested 36 hours after the swab was taken, so if it is delayed in reaching the laboratory, the swab might have to be discarded.

She went on to explain that inmmunoflourescence, another diagnostic method, takes one to two days, and in France, diagnosticians "must return a negative result in the three days after the reception of the swab for analysis." DNA extraction directly on the swab and polymerase chain reaction testing (PCR) takes one day, and PCR directly on the swab without DNA extraction (the new method described in this paper) takes "four hours and half the cost compared with DNA extraction directly on the swab and PCR," said Petry.

"Specificity was determined with 125 isolates of T. equigenitalis, 24 isolates of Taylorella asinigenitalis (a closely related bacterium), five commensal bacteria of the genital tract, and a facultative intracellular pathogen of foals found in large concentration in soil," the authors continued.

Petry added, "Taylorella asinigenitalis is the second bacterium of the genre Taylorella, so T. equigenitalis and T. asinigenitalis were closely related bacteria. This second species is generally called 'Taylorella-like.' It was isolated from a male donkey and wasn't (thought to be) responsible for contagious metritis. Moreover, recent experimental studies prove that T. asinigenitalis can induce contagious metritis on mares and several strains of T. asinigenitalis were already isolated on the genital tract of stallion. So it's very important to watch this second species of Taylorella."

She said that before the new PCR test could have widespread use, the researchers need to add an internal positive control. A similar PCR kit is already on the market in Germany, so Petry suggests it could be beneficial to use the same type of PCR test across Europe.

The study appeared in the June issue of Research in Veterinary Science.

About the Author

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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