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About SickKids

January 16, 2008

Cell biologists find clues to chronic bacterial infection

TORONTO – The January 17, 2008 issue of the prestigious journal, Nature, includes an article by researchers at The Hospital for Sick Children (SickKids), University of Toronto and Harvard Medical School that documents new knowledge about one chronic bacterial infection and suggests a pattern for others.

SickKids scientist Dr. John Brumell and his colleagues studied Listeria monocytogenes, a type of bacteria that causes food poisoning and has serious, even lethal, consequences for pregnant women, young infants, the elderly and people whose immune system is severely weakened. The infection, known as listeriosis, can be acute as well as chronic, and the researchers have found new evidence of how the bacteria sustain a chronic infection.

The discovery could lead to greater understanding of other chronic infections such as tuberculosis and some forms of urinary tract infections and ulcers.

Brumell’s team normally works on Salmonella typhimurium, a different bacterial species. Two years ago they wanted to do a comparison with another bacterium that causes food poisoning. They chose Listeria monocytogenes, which is found in unpasteurized cheese, and this led to a series of questions at the intra-cellular level and conclusions about the toxin, listeriolysin O, that is produced by the bacteria.

Their discovery responds to the long-standing question of how bacteria can cause either acute or chronic infections. “We found that the same toxin, which the bacteria are using to grow rapidly inside one part of the cell and cause a serious and life threatening infection, apparently also allows the bacteria to grow slowly inside another part of the cell and cause a chronic infection,” says Brumell.

While scientists have known for years that the listeriolysin O toxin causes acute infection, Brumell’s study of its role in chronic infections illustrates how central this toxin is for causing disease. He and his team will analyze their findings further and hope eventually to test their thesis on humans.

Infectious diseases are an important area of research at SickKids. Dr. Upton Allen, Head of the Division of Infectious Diseases, says Brumell’s work will increase understanding of chronic infectious diseases. “I think this area of research gives us a better understanding of the how’s and the why’s as they relate to the genesis of some types of infection and will help us in our work to control and prevent these kinds of infections.”

The research was supported by grants from the Burroughs Wellcome Fund, the Boehringer Ingelheim (Canada) Young Investigator Award in Biological Sciences, the Canada Foundation for Innovation, the Ontario Innovation Trust, the Ontario Ministry of Economic Development and Trade, the Natural Sciences and Engineering Research Council of Canada, the Canadian Association of Gastroenterology, and the Canadian Institutes of Health Research.

SickKids, affiliated with the University of Toronto, is Canada’s most research-intensive children’s hospital and the largest centre dedicated to improving children's health in the country. As an innovator in child health, SickKids improves the health of children by integrating care, research and teaching. The mission of SickKids is to provide the best in complex and specialized care by creating scientific and clinical advancements, sharing our knowledge and expertise and championing the development of an accessible, comprehensive and sustainable child health system. For more information, please visit www.sickkids.ca. SickKids is committed to healthier children for a better world.