1. Canadian Bacterial Diseases Network,1
2. Department of Microbiology, University of Guelph, Guelph, Ontario N1G 2W1,2 and
3. Department of Microbiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78284-77583; and
4. Departments of Medicine and Microbiology, University of Washington, Seattle, Washington 981954
5. Centre for the Study of Host Resistance, McGill University, Montreal, Quebec H3G 1A4,5 Canada;