1. Division of Infectious Diseases, Department of Medicine, McMaster University, Hamilton, Ontario, Canada (R.A.O.)
2. Division of Infectious Diseases, Department of Medicine, Division of Medical Microbiology, Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada (M.B.)
3. University of Pennsylvania Perelman School of Medicine, and Annals of Internal Medicine, Philadelphia, Pennsylvania (M.G.S.).