1. Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON K1Y 4E9, Canada
2. School of Epidemiology and Public Health, University of Ottawa, Ottawa, ON K1N 6N5, Canada
3. Faculty of Medicine, University of Ottawa, Ottawa, ON K1N 6N5, Canada
4. Division of Infectious Diseases, Department of Medicine, University of Ottawa, Ottawa, ON K1N 6N5, Canada
5. National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB R2C 3A9, Canada
6. Department of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada