Features
Chemist Maps New Ground Against Deadly Bug
New C. difficile vaccine the goal for CPES, OVC profs in joint research project
BY ANDREW VOWLES
Sugar may help the medicine go down, but what about a medicine that targets sugar to “take down” disease-causing bacteria?
Two U of G researchers are taking this novel route to tackling Clostridium difficile, in hopes of eventually developing a safe, effective vaccine against a bug that has sickened and killed people in hospitals and nursing homes across Canada and has threatened various animal species.
Profs. Mario Monteiro, Chemistry, and Scott Weese, Pathobiology, hope their collaborative studies will ultimately lead to a carbohydrate-based vaccine for both people and animals.
No vaccine currently exists for C. difficile, a major cause of diarrhea, particularly among older people in hospitals and nursing homes. Most people are infected in institutions where commonly used antibiotics kill “good” bacteria in the gut, allowing the problem bug to thrive.
“C. difficile is the most important cause of hospital-associated and antibiotic-associated diarrhea,” says Weese. He says there's evidence that the bacteria also pose a general community health risk and a risk of food-borne disease. Last year, his lab found evidence of C. difficile in ground and processed meats sold in Canada.
Monteiro has mapped out the chemical structure of polysaccharides, or complex chains of sugars, on the surface of the bacteria.
Learning more about the polysaccharides may ultimately help in developing vaccines based on carbohydrates or carbohydrate-protein complexes. The researchers caution that it would take years to develop and test a vaccine for human use.
Monteiro contacted Weese after reading about recent C. difficile outbreaks. Along with PhD student Jeya Ganeshapillai and Evgeny Vinogradov, a scientist at the National Research Council, Monteiro identified the complex bacterial sugars.
“They seem to express similar sugar structures, which will make it easier to develop a vaccine that would target different strains of the bacteria,” he says.
He's also developing sugar-based vaccines against Campylobacter, which causes food poisoning when improperly cooked chicken is eaten, and Helicobacter pylori, a common gut microbe that can cause gastritis, ulcers and stomach cancer. As a graduate student in the mid-1990s, he helped discover the polysaccharide structures in H. pylori.
Monteiro says new commercially available vaccines for pneumococcal and meningococcal diseases are also based on bacterial surface sugars.