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<i>E. coli</i>: The Good, The Bad, The Resistant

11 July 2005, at 12:00am

By Courtney Denard, Ontario Pork - The potential for antibiotic resistance in bacteria has University of Guelph Prof. Patrick Boerlin, Department of Pathobiology, using a genetic approach to try to understand and lessen this occurrence on agricultural operations.

Information provided courtesy Ontario Pork Ontario Pork Logo

July 2005 Newsletter

The Pork, Wine and Cheese Show
National Antimicrobial Resistance Surveillance Program
Youth Ag Career Camp
Ag Energy Offer
Ontario Pork Hires Enforcement Inspector
Hog Days of Summer
First Quarterly Marketing Operations Fee Reimbursement

"Antibiotic resistance can be very problematic," says Boerlin, who's collaborating with researchers at the University of Guelph and the Public Health Agency of Canada. Reduced and more targeted drug treatment on animals, he says, will lead to a decrease in antibiotic resistance in bacteria, allowing producers to save money while creating a healthier community for animals and humans.

Specifically, Boerlin and his collaborators are identifying and locating the bacterial genes responsible for disease and antibiotic resistance in two forms of E. coli bacteria - one good, one bad.

The bad form, pathogenic E. coli, can cause disease in animals. The good form, known as commensal E. coli, isn't a direct threat to human or animal health - but it isn't totally good, either: Boerlin says it can aid in spreading antibiotic resistance genes to harmful bacteria, contributing to swine disease.

The two forms of E. coli can readily exchange genes for antibiotic resistance between one another, says Boerlin - in fact, several genes for resistance to different drugs can be exchanged simultaneously. What's more, resistance genes are sometimes linked with virulence genes, the genes bacteria use to cause diseases. So, resistance in good E. coli may still increase antibiotic resistance levels in both bacteria types.

Knowing more about the linkage between resistance and virulence genes will help researchers develop strategies for more judicious antibiotic use and select appropriate antibiotics for treatment - that is, antibiotics that effectively destroy these virulent bacteria.

The first phase of Boerlin's research consists of sampling and characterizing several hundred different E. coli strains isolated from Ontario pigs. By studying how genes are distributed in the bacterial genome, he can identify the linkages between resistance genes for different antibiotics, and between resistance and virulence genes.

Boerlin and his collaborators will compare bacterial samples obtained from animals treated with tetracycline (an antibiotic commonly used in swine) to samples from untreated animals, to determine how antibiotic use affects the spread of linked resistance and virulence genes - and of the bacteria carrying them - in pigs housed in University of Guelph's isolation unit. They're currently developing and validating molecular methods for these experiments, which they hope will later become useful tools for diagnostic laboratories.

This research is funded by Ontario Pork, the Canada Foundation for Innovation, the Ontario Innovation Trust, the Public Health Agency of Canada and the Ontario Ministry of Agriculture and Food.

Source: Ontario Pork - July 2005

Judy Maus is a writer with SPARK, the University of Guelph’s student writing program.