How do you screen for TB

PPD: > 5 induration for HIV, Fibrotic changes on CXR, Recent contact with active case or immunocompromised. > 15 if no risk factors, and > 10 for all others and IGRA ( Interferron Gamma Release Assay) or Quantiferon TB Gold and TSPOT. Use this assay for pt who will not show for f/u. and for hx of BCG vaccine.