[1] Univ Calif Davis, Med Ctr, Dept Internal Med, Div Infect & Immunol Dis, Sacramento, CA 95817 USA
[2] Loyola Univ Chicago Stritch Sch Med, Res Serv, Vet Affairs Edward Hines Jr Hosp, Maywood, IL USA
[3] Loyola Univ Chicago Stritch Sch Med, Div Infect Dis, Dept Med, Maywood, IL USA
[4] Beth Israel Deaconess Med Ctr, Div Gastroenterol, Boston, MA 02215 USA
[5] McGill Univ, Dept Microbiol, Ctr Hlth, Montreal, PQ H3A 2T5, Canada
[6] Ctr Dis Control & Prevent, Div Healthcare Qual Promot, Natl Ctr Preparedness Detect & Control Infect Dis, Atlanta, GA USA
[7] Univ Sherbrooke, Dept Microbiol & Infect Dis, Quebec City, PQ, Canada
[8] Univ Leeds, Dept Microbiol, Leeds Teaching Hosp Natl Hlth Serv Trust, Leeds LS2 9JT, W Yorkshire, England
[9] Univ Leeds, Inst Mol & Cellular Biol, Leeds LS2 9JT, W Yorkshire, England