SUMMARY
●Identification and treatment of individuals with latent tuberculosis infection (LTBI) is an important priority for tuberculosis (TB) control. The approach to diagnosis of LTBI is discussed separately. (See "Approach to diagnosis of latent tuberculosis infection (tuberculosis screening) in adults".)
●LTBI is a clinical diagnosis that is established by demonstrating prior tuberculosis infection and excluding active tuberculosis disease [58]. Available tests to demonstrate prior tuberculosis infection include the tuberculin skin test (TST) and interferon-gamma release assays (IGRAs) (table 1). Issues related to use of TST are discussed separately. (See "Use of the tuberculin skin test for diagnosis of latent tuberculosis infection (tuberculosis screening) in adults".)
●IGRAs are diagnostic tools for LTBI. They are in vitro blood tests of cell-mediated immune response to Mycobacterium tuberculosis and measure T cell release of interferon-gamma following stimulation by antigens specific to M. tuberculosis. (See 'Introduction' above.)
●There are two major IGRAs available: the QuantiFERON-TB Gold In-Tube (QFT-GIT) assay and the T-SPOT.TB assay. QFT-GIT is an enzyme-linked immunosorbent assay (ELISA)-based whole blood test. T-SPOT.TB is an enzyme-linked immunospot (ELISPOT) performed on separated peripheral blood mononuclear cells (PBMCs). (See 'Types of assays' above.)
●IGRAs are not affected by Bacille Calmette-Guérin (BCG) vaccination status and have specificity >95 percent for diagnosis of LTBI. IGRAs are preferred for patients with history of BCG vaccination, especially if received in countries where BCG is given after infancy or repeated. (See 'Use of IGRAs' above.)
●The sensitivity for T-SPOT.TB appears to be higher than QFT-GIT or TST, likely because the testing platform ensures that an adequate number of peripheral blood mononuclear cells are available even in the presence of low lymphocyte cell counts in whole blood. (See 'Sensitivity and specificity' above.)
●IGRAs cannot distinguish between latent infection and active TB disease and should not be used for diagnosis of active TB. A negative IGRA does not rule out active TB at any age. (See 'General principles' above.)
●For serial testing in populations exposed to TB, data are insufficient for interpretation of IGRA conversions and reversions, and several studies suggest poor assay reproducibility. (See 'Serial testing' above.)
●Identification and treatment of individuals with latent tuberculosis infection (LTBI) is an important priority for tuberculosis (TB) control. The approach to diagnosis of LTBI is discussed separately. (See "Approach to diagnosis of latent tuberculosis infection (tuberculosis screening) in adults".)
●LTBI is a clinical diagnosis that is established by demonstrating prior tuberculosis infection and excluding active tuberculosis disease [58]. Available tests to demonstrate prior tuberculosis infection include the tuberculin skin test (TST) and interferon-gamma release assays (IGRAs) (table 1). Issues related to use of TST are discussed separately. (See "Use of the tuberculin skin test for diagnosis of latent tuberculosis infection (tuberculosis screening) in adults".)
●IGRAs are diagnostic tools for LTBI. They are in vitro blood tests of cell-mediated immune response to Mycobacterium tuberculosis and measure T cell release of interferon-gamma following stimulation by antigens specific to M. tuberculosis. (See 'Introduction' above.)
●There are two major IGRAs available: the QuantiFERON-TB Gold In-Tube (QFT-GIT) assay and the T-SPOT.TB assay. QFT-GIT is an enzyme-linked immunosorbent assay (ELISA)-based whole blood test. T-SPOT.TB is an enzyme-linked immunospot (ELISPOT) performed on separated peripheral blood mononuclear cells (PBMCs). (See 'Types of assays' above.)
●IGRAs are not affected by Bacille Calmette-Guérin (BCG) vaccination status and have specificity >95 percent for diagnosis of LTBI. IGRAs are preferred for patients with history of BCG vaccination, especially if received in countries where BCG is given after infancy or repeated. (See 'Use of IGRAs' above.)
●The sensitivity for T-SPOT.TB appears to be higher than QFT-GIT or TST, likely because the testing platform ensures that an adequate number of peripheral blood mononuclear cells are available even in the presence of low lymphocyte cell counts in whole blood. (See 'Sensitivity and specificity' above.)
●IGRAs cannot distinguish between latent infection and active TB disease and should not be used for diagnosis of active TB. A negative IGRA does not rule out active TB at any age. (See 'General principles' above.)
●For serial testing in populations exposed to TB, data are insufficient for interpretation of IGRA conversions and reversions, and several studies suggest poor assay reproducibility. (See 'Serial testing' above.)
No comments:
Post a Comment