[1] Karolinska Univ Hosp, Dept Med, Infect Dis Unit, S-14186 Huddinge, Sweden
[2] Swedish Inst Infect Dis Control, Dept Mol Epidemiol & Biotechnol, Stockholm, Sweden
[3] 2J2 00 Walter C Mackenzie Hlth Sci Ctr, Edmonton, AB 6 27, Canada
[4] Marshall Univ, John C Edwards Sch Med, Dept Med, Huntington, WV 25701 USA
[5] Hosp Clin Barcelona, Inst Clin Pneumol & Cirurg Torac, E-08036 Barcelona, Spain
[6] Manchester Royal Infirm, Dept Resp Med, Manchester M13 9WL, Lancs, England