Comparison between quantiferon-TB-gold test and tuberculin skin testing in diagnosis of both latent and active tuberculosis infections

ABSTRACT

Introduction: Tuberculosis [TB] is an infectious disease affecting mostly the respiratory system with or without affection of other organ-systems caused mainly by infection with Mycobaterial tuberculosis [MTB]. However, not all cases of infection with any of the TB bacilli are converted to active or manifested infection and most cases are called latent tuberculosis infection [LTBI] which can be later on converted to active infection. There are several factors that underline the conversion from latent to active TB infections. Previously LTBIs was diagnosed by tuberculin skin testing [TST] but now there is new test formats which measures the released interferon-y [INF-y] after stimulation ofT-cells contained in whole patient blood by specific antigens obtained from MTB. These tests are called interferon gamma release assays [IGRAs] which are more sensitive and specific than TST one of these tests is the QuantiFERON-TB Gold In-Tube [QFT-G] which measures the released IFN-y by ELISA method: