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Chapter/Section
Page Title
Page
TST
IGRA
Tuberculin is injected under the skin and produces a delayed-type hypersensitivity reaction if the person has been infected with M. tuberculosis
Blood is drawn for testing; test measures the immune response to the TB bacteria in whole blood
Requires two or more patient visits to conduct the test
Requires one patient visit to conduct the test
Results are available 48 to 72 hours later
Results can be available in 24 hours (depending on the batching of specimens by the laboratory and transport)
Can cause boosted reaction
Does not cause boosted reaction
Reading by HCW may be subjective
Laboratory test not affected by HCW perception or bias
BCG vaccination can cause false-positive result
BCG vaccination does not cause
false-positive result and infection with most nontuberculous mycobacteria does not cause false-positive result
A negative reaction to the test does not exclude the diagnosis of LTBI or TB disease
A negative reaction to the test does not exclude the diagnosis of LTBI or TB disease
For more information on IGRAs please review the IGRA section in this chapter.