tuberculinereacties

Tuberculinereacties, also known as tuberculin skin tests orTSTs, are diagnostic procedures used to detect latent tuberculosis infection. The most common type is the Mantoux tuberculin skin test. This involves injecting a small amount of tuberculin purified protein derivative (PPD) into the outer layer of the forearm. The body's immune response to the PPD, if it has previously been exposed to Mycobacterium tuberculosis, will cause a localized reaction at the injection site.

After an incubation period of 48 to 72 hours, a trained healthcare professional examines the site for induration, which is a raised, hardened swelling. The size of the induration, measured in millimeters, determines the result of the test. A significant induration indicates a positive reaction, suggesting that the person has been infected with tuberculosis bacteria. However, a positive TST does not differentiate between active tuberculosis disease and latent tuberculosis infection (LTBI), where the bacteria are present but not causing active illness.

False-positive reactions can occur in individuals who have received the BCG vaccine or have been infected with non-tuberculous mycobacteria. False-negative reactions can occur in individuals with weakened immune systems, recent tuberculosis infection, or overwhelming active disease. Therefore, TST results are often interpreted in conjunction with a person's medical history, physical examination, and other diagnostic tests, such as chest X-rays or sputum cultures, to confirm a diagnosis of active tuberculosis.