[1] Postgrad Inst Med Educ & Res, Dept Pulm Med, Chandigarh, India
[2] CK Birla Hosp, Dept Pulmonol, Kolkata, India
[3] Imperial Coll, Fac Med, Dept Infect Dis, London, England
[4] Postgrad Inst Med Educ & Res, Dept Pulm Med, Sect 12, Chandigarh 160012, India