[1] McMaster Univ, Div Infect Dis & Med Microbiol, Hamilton, ON, Canada
[2] Hamilton Civ Hosp, Hamilton, ON, Canada
[3] St Louis Univ, Sch Med, Dept Internal Med, St Louis, MO USA
[4] St Louis Vet Affairs VA Med Ctr, Ctr Geriatr Res Educ & Clin, St Louis, MO USA
[5] VA Med Ctr, GRECC, Ann Arbor, MI USA
[6] VA Med Ctr, Educ Serv, Minneapolis, MN USA
[7] Polyclin Med Ctr, Dept Med, Harrisburg, PA USA
[8] Univ Connecticut, Ctr Hlth, Dept Med, Farmington, CT USA
[9] Mt Sinai Hosp, Dept Infect Control, Toronto, ON M5G 1X5, Canada
[10] Univ Toronto, Toronto, ON, Canada
[11] Univ Pittsburgh, Med Ctr, VA Pittsburgh Healthcare Syst, Pittsburgh, PA 15260 USA
[12] Erie Cty Med Ctr, Buffalo, NY USA
[13] Univ Manitoba, Dept Med, Hlth Sci Ctr, Winnipeg, MB R3T 2N2, Canada
[14] Hosp Special Care, New Britain, CT USA
[15] Hlth Canada, Lab Ctr Dis Prevent & Control, Ottawa, ON K1A 0L2, Canada
[16] Sunnybrook & Womens Coll, Hlth Sci Ctr, Toronto, ON, Canada
[17] Univ Toronto, Toronto, ON, Canada
[18] Univ Nebraska, Med Ctr, Omaha, NE USA
[19] Portland VA Med Ctr, Portland, OR USA