Preserving Feces to Improve C. perfringens Diagnosis

Preserving Feces to Improve <i>C. perfringens</i> Diagnosis

Clostridium perfringens (type C) is a bacterium that causes severe diarrhea in horses and is one of the most common causes of neonatal diarrhea.

Photo: Anne M. Eberhardt/The Horse

Diagnosing Clostridium perfringens infections in horses has taken a step forward, thanks to recent study results identifying two methods that extend the life of the bacteria contained in fecal samples from days to weeks.

Clostridium perfringens (type C) is a bacterium that causes severe diarrhea in horses and is one of the most common causes of neonatal diarrhea. A veterinarian makes a final diagnosis only if he or she can detect the toxin C. perfringens produces, called CPB, in diarrheic horses' intestinal contents or feces.

"The problem is that the toxin is very sensitive to the action of trypsin and other enzymes in the intestinal contents, and CPB only persists for a limited time in the intestinal contents, like fecal matter, collected from horses," explains Francisco Uzal, DVM, PhD, a professor of clinical diagnostic pathology at the University of California, Davis, California Animal Health and Food Safety Laboratory System, in San Bernardino. This means that by the time the sample arrives at the lab, the CPB could have already degraded to the point of being undetectable, thus eliminating the chance of a positive diagnosis.

Because a firm diagnosis in diarrheic horses is important to instituting proper treatment and infection control/prevention techniques, Uzal and colleagues studied equine fecal samples "spiked" with CPB to determine how temperature and trypsin inhibitors impacted CPB detection.

"When intestinal contents known to have CPB were stored at 4°C (39°F), CPB could only be detected for eight days using a standard test called a capture ELISA," said Uzal. "Storing samples at -20°C (-4°F) or adding a trypsin inhibitor preserves the lifespan of CPB for at least five weeks."

Armed with this new information, veterinarians such as ambulatory practitioners unable to have samples immediately tested, can now preserve samples via freezing and trypsin inhibitor and minimize CPB degradation to obtain more accurate diagnostic test results.

The study, "Freezing or adding trypsin inhibitor to equine intestinal contents extends the lifespan of Clostridium perfringens beta toxin for diagnostic purposes," will be published in an upcoming edition of the journal Anaerobe. The abstract can be viewed online.

About the Author

Stacey Oke, DVM, MSc

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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