Mycobacterium tuberculosis IGRA

Keywords: Interferon-gamma assay for Mycobacterium tuberculosis, IGRA Mycobacterium tuberculosis

Specimen:

10 mL of blood in sodium or lithium heparin tube or 1 mL directly into three specialised collection tubes. Consult laboratory for local arrangements, since specific time limits and transport conditions need to be satisfied.

Method:

EIA measurement of interferon-gamma after incubation of the specimen with Mycobacterium tuberculosis antigens.

Application:

Investigation for exposure to, or infection with, tuberculosis.

Interpretation:

A positive interferon-gamma response to antigens present in the assay indicates either active or latent infection with Mycobacterium tuberculosis. Occasional false negatives may occur, especially in early disease or infection in immunocompromised individuals. Rare false positives may occur due to infection with M. kansasii, M. marinum or M. szulgai, but not as a result of previous BCG vaccination.

Reference:

Muzurek GH et al. Morb Mortal Wkly Report. 2005: 54 (RR-15):49-55