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Tuberculin Skin Test (TST)

  • TST is used to screen for TB infection and not to diagnose TB disease
  • TSTs are mostly used to detect LTBI in children.
  • Tuberculin is a purified protein derivative (PPD) of tubercle bacilli.
  • A person infected with M. tuberculosis develops hypersensitivity to tuberculin, which, when injected into the skin of an infected person, produces a delayed local reaction after 48 hours.
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