U of G team finds that the same strains of C. difficile may infect animals and humans
BY ANDREW VOWLES
Helping doctors learn more about a bug that has killed more than 100 people in Montreal and Sherbrooke-area hospitals this year is one goal of several OVC researchers studying gut ailments in horses and other animals.
Profs. Henry Staempfli and Scott Weese, Clinical Studies, and post-doctoral researcher Luis Arroyo are working with microbiologists in Quebec and Ontario to learn more about deadly strains of Clostridium difficile. The death rate from the bacterium is higher than formerly believed.
Analysing C. difficile may help in attempts to prevent or reduce the incidence of disease, says Weese, although he cautions that confirming interspecies transmission will not necessarily have a major impact on human disease.
“We don't know whether interspecies transmission is a serious problem or not,” he says. “Most C. difficile cases are hospital in origin, and the chance of animal exposure is limited. Interspecies transmission could be more important on a population basis if animals could be reservoirs of important strains.”
Weese says the Guelph group was asked for help in studying the bug by researchers at hospitals in Quebec and at Mount Sinai Hospital in Toronto.
The U of G team hopes their discovery that the same strains of C. difficile may infect animals and humans — research to be published in the Journal of Medical Microbiology — will help in understanding and attacking the problem.
Weese, who began studying C. difficile seven years ago while completing his own D.V.Sc. degree with Staempfli, says few labs have worked on this organism.
Arroyo looked at it in horses for his D.V.Sc. work with Weese, who has also evaluated C. difficile in dogs. Another D.V.Sc. student is now studying the organism in calves.
The researchers use a DNA fingerprinting technique called PCR ribotyping to differentiate between strains of bacteria. They found that different strains predominate in various mammals.
More important, they learned that several strains were common to different mammal species, suggesting that the bug passes between species.
“But confirming interspecies transmission is difficult,” Weese says.
Animals and humans may carry C. difficile in their gut without suffering illness. But antibiotics used to treat various diseases may throw the normal balance of gut organisms out of whack, allowing C. difficile to flourish. If permitted to grow out of control, the bacterium may make enough toxins to cause illness, particularly in people who are on antibiotics or chemotherapy or who are elderly.
“Hygiene is still the number one tool or the best fighter against it,” says Arroyo.
