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Monday, July 9, 2012

Diagnostic Test/Procedure: Mantoux TB Skin Test

The Mantoux test (also known as the Mantoux screening test, tuberculin sensitivity test, Pirquet test, or PPD test for purified protein derivative) is a diagnostic tool for tuberculosis. It is one of the major tuberculin skin tests used around the world, largely replacing multiple-puncture tests such as the Tine test. The Heaf test was used until 2005 in the UK, when it was replaced by the Mantoux test. It is endorsed by the American Thoracic Society and Centers for Disease Control and Prevention.

Classification of Tuberculin Reaction

The results of this test must be interpreted carefully. The person's medical risk factors determine at which increment (5 mm, 10 mm, or 15 mm) of induration the result is considered positive. A positive result indicates TB exposure.

5 mm or more is positive in
  • An HIV-positive person
  • Persons with recent contacts with a TB patient
  • Persons with nodular or fibrotic changes on chest X-ray consistent with old healed TB
  • Patients with organ transplants, and other immunosuppressed patients

10 mm or more is positive in
  • Recent arrivals (less than five years) from high-prevalence countries
  • Injection drug users
  • Residents and employees of high-risk congregate settings (e.g., prisons, nursing homes, hospitals, homeless shelters, etc.)
  • Mycobacteriology lab personnel
  • Persons with clinical conditions that place them at high risk (e.g., diabetes, prolonged corticosteroid therapy, leukemia, end-stage renal disease, chronic malabsorption syndromes, low body weight, etc.)
  • Children less than four years of age, or children and adolescents exposed to adults in high-risk categories

15 mm or more is positive in
  • Persons with no known risk factors for TB

Ø  This is used to determine if a person has been infected or has been exposed to the TB bacillus.
Ø  This utilizes the PPD (Purified Protein Derivatives).
Ø  The PPD is injected intradermally usually in the inner aspect of the lower forearm about 4 inches below the elbow. 
Ø  The test is read 48 to 72 hours after injection.
Ø  (+) Mantoux Test is induration of 10 mm or more.
Ø  But for HIV positive clients, induration of about 5 mm is considered positive
Ø  Signifies exposure to Mycobacterium Tubercle bacilli

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