Mantoux testing

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