[1] Royal Infirm Edinburgh NHS Trust, Dept Resp Med, Edinburgh EH16 4SA, Midlothian, Scotland
[2] Univ Edinburgh, Sch Med & Vet Med, Cyst Fibrosis Grp, Ctr Infect Dis, Edinburgh, Midlothian, Scotland
[3] Univ Edinburgh, MRC Ctr Inflammat Res, Queens Med Res Inst, Edinburgh, Midlothian, Scotland
[4] Western Gen Hosp, Dept Resp Med, Edinburgh EH4 2XU, Midlothian, Scotland