Mantoux testing


Mantoux should raise bleb confirming intradermal injection
  • 2TU injected intradermally (MUST raise bleb)
  • Area induration measured at 48h
  • May take 2-12 weeks after 1° infection for skin conversion
  • >5 mm - considered positive in
    • HIV-positive persons
    • Recent contacts of TB case patients
    • CXR consistent with prior TB
    • On immunosuppressants
  • >15 mm - positive in everyone else
  • False negatives
    • Inadequate nutrition
    • Immunosuppressed
    • Severe TB (e.g. miliary disease)
    • Concurrent viral infection
    • Corticosteroid therapy
Positive mantoux at 48 hours

Content by Dr Íomhar O' Sullivan 20/01/2008. Last review Dr ÍOS 10/06/21.