Tuberculin purified protein derivative

How it works

Intradermal antigen elicits a delayed-type hypersensitivity response in sensitised individuals, producing a measurable area of skin induration after a defined interval.

Prescribing in practice

• It must be given strictly intradermally and the result read as induration at the specified time, as incorrect technique or timing invalidates interpretation.
• Results require clinical interpretation, since prior BCG vaccination, some infections, and immunosuppression can cause false-positive or false-negative reactions.
• A positive test indicates immune sensitisation and does not by itself distinguish latent infection from active tuberculosis disease.

Monitoring

Ensure the reaction is read by trained staff at the correct interval, measuring induration rather than erythema, and interpret alongside the clinical picture.

Counselling the patient

• You must return at the specified time to have the test site measured.
• A raised firm area, not redness alone, is what is measured.
• The result will be interpreted together with your history and other tests.

Evidence & guidelines

The Mantoux tuberculin test is the standard intradermal method for assessing tuberculosis infection in UK NICE and Health Security Agency guidance.