Tuberculin

Tuberculin is a skin test used to diagnose infection with Mycobacterium tuberculosis, the bacterium that causes tuberculosis (TB). The test involves injecting a small amount of a protein derived from the bacteria beneath the skin of a person's forearm. The test results are read 48-72 hours later. If the person has been infected with the TB bacterium, a reaction occurs resulting in a raised, red and sometimes hard lump at the injection site. This indicates a positive result for TB infection. Tuberculin testing is used to diagnose TB in people who are currently infected and as a tool to screen people at risk of developing TB.