Tuberculosis
Tuberculosis ( 23 Questions)
The Interferon-gamma release assay (IGRA) is another test used to detect TB infection. It measures the release of interferon-gamma by T-cells in response to TB antigens. However, in this question, the specific test described involves injecting tuberculin into the forearm, which is the characteristic of the TST, not the IGRA.
Chest x-ray is not a test used to detect TB infection directly. It is useful for identifying active pulmonary TB, but it does not detect latent TB infection, which is what the tuberculin skin test is designed for.
Sputum smear microscopy is a test used to diagnose active TB by examining sputum samples for acid-fast bacilli. It is not used for detecting latent TB infection, as the tuberculin skin test does.
The tuberculin skin test (TST), also known as the Mantoux test, involves injecting a small amount of tuberculin into the forearm and then measuring the induration (localized swelling and redness) at the injection site after 48 to 72 hours. A positive TST result indicates exposure to TB but does not distinguish between latent TB infection and active TB disease.
Choice A rationale:
The Interferon-gamma release assay (IGRA) is another test used to detect TB infection. It measures the release of interferon-gamma by T-cells in response to TB antigens. However, in this question, the specific test described involves injecting tuberculin into the forearm, which is the characteristic of the TST, not the IGRA.
Choice B rationale:
Chest x-ray is not a test used to detect TB infection directly. It is useful for identifying active pulmonary TB, but it does not detect latent TB infection, which is what the tuberculin skin test is designed for.
Choice C rationale:
Sputum smear microscopy is a test used to diagnose active TB by examining sputum samples for acid-fast bacilli. It is not used for detecting latent TB infection, as the tuberculin skin test does.
Choice D rationale:
The tuberculin skin test (TST), also known as the Mantoux test, involves injecting a small amount of tuberculin into the forearm and then measuring the induration (localized swelling and redness) at the injection site after 48 to 72 hours. A positive TST result indicates exposure to TB but does not distinguish between latent TB infection and active TB disease.