SEARCHED TERM
Boosting
DEFINITION
Phenomenon in which some persons who receive a tuberculin skin test (TST) many years after acquiring M. tuberculosis infection have a negative result to an initial TST followed by a positive result to a subsequent TST. The second (i.e. positive) result is caused by a boosted immune response of the prior sensitivity rather than a new infection.
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SOURCE DEFINITION
Phenomenon in which some persons who receive a TST many years after acquiring latent TB infection (LTBI) have a negative result to an initial TST followed by a positive result to a subsequent TST. The second (i.e., positive) result is caused by a boosted immune response of the prior sensitivity rather than by a new infection. Two-step testing is used to distinguish new infections from boosted reactions in TB infection control screening programs that utilize TST for detecting M. tuberculosis (see Two-step skin testing). Because QuantiFERON®-TB Gold (QFT-G) test is an in vitro method, it is not complicated by boosting
OTHER DEFINITIONS
Initially limited reaction size followed by a larger reaction size on a later test, which can be confused with a conversion or a recent M. tuberculosis infection. This is happening when nonspecific or remote sensitivity to tuberculin (purified protein derivative [PPD] in the skin test) wanes or disappears with time, subsequent tuberculin skin tests can restore the sensitivity. Two-step testing is used to distinguish new infections from boosted reactions in infection-control surveillance programs, but this method is not recommended for testing contacts
Phenomenon in which a person has a negative TST (i.e., false-negative) result years after infection with M. tuberculosis and then a positive subsequent TST result. The positive TST result is caused by a boosted immune response of previous sensitivity rather than by a new infection (false-positive TST conversion). Two-step testing reduces the likelihood of mistaking a boosted reaction for a new infection
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