1. Pneumology Service, Hospital of Specialties at the National Medical Center of the West (IMSS) , Guadalajara , México
2. Medical Didactic Unit, Autonomous University of Aguascalientes , Aguascalientes , México
3. Department of Medicine, Autonomous University of Aguascalientes , Aguascalientes , México
4. Department of Microbiology and Immunology, University of Western Ontario , London, ON , Canada
5. Pneumology Service, Institute of Security and Social Services for State Workers , Aguascalientes , México