[1] McMaster Univ, Henderson Hosp, Div Infect Dis, Hamilton, ON L8V 1C3, Canada
[2] McMaster Univ, Sch Med, Hamilton, ON L8V 1C3, Canada
[3] Northwestern Univ, Feinberg Sch Med, Chicago, IL 60611 USA
[4] Univ Texas, Hlth Sci Ctr, San Antonio, TX 78285 USA
[5] S Texas Vet Hlth Care Syst, San Antonio, TX 78285 USA
[6] Michael E DeBakey VA Med Ctr, Houston, TX USA
[7] Baylor Coll Med, Houston, TX 77030 USA
[8] Johns Hopkins Univ, Sch Med, Baltimore, MD 21218 USA
[9] Univ Mississippi, Sch Med, Div Pulm Crit Care & Sleep Med, Jackson, MS 39216 USA
[10] LDS Hosp, Div Pulm & Crit Care Med, Salt Lake City, UT USA
[11] Univ Utah, Salt Lake City, UT USA
[12] Ctr Dis Control & Prevent, Atlanta, GA USA
[13] NW Ohio Univ, Coll Med, Rootstown, OH USA
[14] Summa Hlth Syst, Akron, OH USA
[15] SUNY Stony Brook, Stony Brook, NY 11794 USA
[16] Winthrop Univ Hosp, Dept Med, Mineola, NY 11501 USA
[17] Univ Barcelona, Fac Med, Inst Invest Biomed August Pi & Sunyer, Hosp Clin Barcelona,Cap Serv Pneumol & Allergia R, Barcelona 7, Spain