Mantoux testing


  • 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
Mantoux should raise bleb confirming intradermal injection
Mantoux injection
Positive mantoux at 48 hours
Mantoux positive

Content by Dr Íomhar O' Sullivan. Last review Dr ÍOS 22/11/22.