1. Department of Clinical Studies, University of Guelph, Guelph, Ontario, Canada
2. Department of Microbiology, Mt. Sinai Hospital, Toronto, Ontario, Canada
3. Ontario Public Health Laboratories, Toronto, Ontario, Canada
4. Department of Pathobiology, University of Guelph, Guelph, Ontario, and National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada