CONTEXT: A recently developed whole-blood interferon gamma (IFN-gamma) assay based on stimulation with the Mycobacterium tuberculosis-specific antigens early secreted antigenic target 6 and culture filtrate protein 10 shows promise for the diagnosis of latent tuberculosis (TB) infection. OBJECTIVE: To compare the tuberculin skin test (TST) and the whole-blood IFN-gamma assay in the diagnosis of latent TB infection according to the intensity of exposure. DESIGN AND SETTING: A prospective comparison between the whole-blood IFN-gamma assay and the TST using a 2-TU dose of purified protein derivative RT23 in a population with intermediate TB burden was conducted sequentially between February 1, 2004, and February 28, 2005, in a Korean tertiary referral hospital. PARTICIPANTS: Of 273 participants, 220 (95.7%) had received BCG vaccine. Participants were grouped according to their risk of infection: group 1, no identifiable risk of M tuberculosis infection (n = 99); group 2, recent casual contacts (n = 72); group 3, recent close contacts (n = 48); group 4, bacteriologically or pathologically confirmed TB patients (n = 54). MAIN OUTCOME MEASURES: Levels of agreement between the TST and the IFN-gamma assay and the likelihood of infection in the various groups. RESULTS: For the TST with a 10-mm induration cutoff, the positive response rate in group 1 was 51%; group 2, 60%; group 3, 71%, and group 4, 78%. For the IFN-gamma assay, the positive response rate in group 1 was 4%; group 2, 10%; group 3, 44%; and group 4, 81%. The overall agreement between the TST and the IFN-gamma assay in healthy volunteers was kappa = 0.16. The odds of a positive test result per unit increase in exposure across the 4 groups increased by a factor of 5.31 (95% confidence interval [CI], 3.62-7.79) for the IFN-gamma assay and by a factor of 1.52 (95% CI, 1.20-1.91) for the TST (P<.001). Using a 15-mm induration cutoff for the TST did not make a substantial difference to the test results. CONCLUSION: The IFN-gamma assay is a better indicator of the risk of M tuberculosis infection than TST in a BCG-vaccinated population.
CONTEXT: A recently developed whole-blood interferon gamma (IFN-gamma) assay based on stimulation with the Mycobacterium tuberculosis-specific antigens early secreted antigenic target 6 and culture filtrate protein 10 shows promise for the diagnosis of latent tuberculosis (TB) infection. OBJECTIVE: To compare the tuberculin skin test (TST) and the whole-blood IFN-gamma assay in the diagnosis of latent TB infection according to the intensity of exposure. DESIGN AND SETTING: A prospective comparison between the whole-blood IFN-gamma assay and the TST using a 2-TU dose of purified protein derivative RT23 in a population with intermediate TB burden was conducted sequentially between February 1, 2004, and February 28, 2005, in a Korean tertiary referral hospital. PARTICIPANTS: Of 273 participants, 220 (95.7%) had received BCG vaccine. Participants were grouped according to their risk of infection: group 1, no identifiable risk of M tuberculosis infection (n = 99); group 2, recent casual contacts (n = 72); group 3, recent close contacts (n = 48); group 4, bacteriologically or pathologically confirmed TBpatients (n = 54). MAIN OUTCOME MEASURES: Levels of agreement between the TST and the IFN-gamma assay and the likelihood of infection in the various groups. RESULTS: For the TST with a 10-mm induration cutoff, the positive response rate in group 1 was 51%; group 2, 60%; group 3, 71%, and group 4, 78%. For the IFN-gamma assay, the positive response rate in group 1 was 4%; group 2, 10%; group 3, 44%; and group 4, 81%. The overall agreement between the TST and the IFN-gamma assay in healthy volunteers was kappa = 0.16. The odds of a positive test result per unit increase in exposure across the 4 groups increased by a factor of 5.31 (95% confidence interval [CI], 3.62-7.79) for the IFN-gamma assay and by a factor of 1.52 (95% CI, 1.20-1.91) for the TST (P<.001). Using a 15-mm induration cutoff for the TST did not make a substantial difference to the test results. CONCLUSION: The IFN-gamma assay is a better indicator of the risk of M tuberculosis infection than TST in a BCG-vaccinated population.
Authors: Baha Abdalhamid; Steven H Hinrichs; Jodi L Garrett; Jean M O'Neill; Kristine M Hansen-Cain; Amy A Armbrust; Peter C Iwen Journal: J Clin Microbiol Date: 2010-06-23 Impact factor: 5.948
Authors: S A Clark; S L Martin; A Pozniak; A Steel; B Ward; J Dunning; D C Henderson; M Nelson; B Gazzard; P Kelleher Journal: Clin Exp Immunol Date: 2007-08-02 Impact factor: 4.330
Authors: Patricia R Blank; Andreas U Freiburghaus; Bernhard R Ruf; Matthias M Schwenkglenks; Thomas D Szucs Journal: Med Klin (Munich) Date: 2009-01-23
Authors: K Okada; T E Mao; T Mori; T Miura; T Sugiyama; T Yoshiyama; S Mitarai; I Onozaki; N Harada; S Saint; K S Kong; Y M Chhour Journal: Epidemiol Infect Date: 2007-11-08 Impact factor: 2.451