Routine hospital use of a new commercial whole blood interferon-γ assay for the diagnosis of tuberculosis infection

Giovanni Ferrara, Monica Losi, Marisa Meacci, Barbara Meccugni, Roberto Piro, Pietro Roversi, Barbara Maria Bergamini, Roberto D'Amico, Patrizia Marchegiano, Fabio Rumpianesi, Leonardo M. Fabbri, Luca Richeldi

Research output: Contribution to journalArticlepeer-review


Rationale: Interferon (IFN)-γ blood tests may improve the current level of diagnostic accuracy for tuberculosis infection. The Quanti-FERON-TB Gold (QFT-Gold) has been used in selected populations and shows higher specificity than the tuberculin skin test (TST). Objective: To evaluate the QFT-Gold test in unselected patients and assess the level of agreement with the TST. Methods: The test has been routinely performed on whole blood samples in our microbiology laboratory for 8 months. Demographic, clinical, and microbiological data have been collected and correlated to the QFT-Gold results. Measurements and Main Results: Of 318 patients tested, 68 (21.4%) gave an indeterminate (low positive mitogen control) QFT-Gold result. Indeterminate results were significantly overrepresented in patients with a negative TST (28.9% vs. 6.6% in TST positive patients; p <0.0001, χ2 test) and were more frequent in patients receiving immunosuppressive therapies than in those who were not receiving such treatments (odds ratio, 3.35; 95% confidence interval, 1.84-6.08; p <0.0001). After excluding indeterminate results, the concordance between QFT-Gold and TST was significantly lower in Bacille Calmette-Guérin-vaccinated individuals (41.5%) than in nonvaccinated individuals (80.3%) (p <0.0001). In 11 patients with active tuberculosis (5 culture-confirmed), QFT-Gold provided more positive results than the TST (66.7% vs. 33.3%; p = 0.165). Conclusions: The QFT-Gold test is feasible in routine hospital use for the diagnosis of tuberculosis infection. As with the TST, immunosuppression may negatively affect the test's performance, with a significant rate of indeterminate results in the most vulnerable population.

Original languageEnglish
Pages (from-to)631-635
Number of pages5
JournalAmerican Journal of Respiratory and Critical Care Medicine
Issue number5
Publication statusPublished - Sep 1 2005


  • Diagnosis
  • Immunosuppression
  • Interferon-γ
  • Tuberculosis

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine


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