Interferon-gamma release assay clarifies the effect of bacille Calmette-Guérin vaccination in Greek army recruits

Int J Tuberc Lung Dis. 2010 May;14(5):545-50.


Objective: To compare the most recent commercial interferon-gamma release assay (IGRA), the QuantiFERON-TB Gold In-Tube (QFT-GIT), with the tuberculin skin test (TST) in Greek army recruits who were bacille Calmette-Guérin (BCG) vaccinated during childhood and had no history of tuberculosis (TB) exposure.

Method: We conducted a cross-sectional comparison study of 1750 young army recruits. TST was performed on all participants, while QFT-GIT was performed in all subjects with TST > 0 mm and in 18 TST-negative controls (TST = 0 mm).

Results: Among the study subjects, 5.4% (96/1750) had TST indurations of >or=10 mm, and 3.4% (59/1750) had indurations of >or=15 mm. Among subjects with a positive TST, 11.4% (11/96) tested positive on QFT-GIT. All those with QFT-GIT positivity had TST indurations of >or=15 mm, and none of those with TST indurations of 10-14 mm were positive by QFT-GIT. The overall agreement between TST and QFT-GIT was poor (kappa = 0.02).

Conclusion: We found a significant discordance between TST and QFT-GIT in BCG-vaccinated Greek army recruits consistent with previous studies showing that BCG received after infancy produces false-positive TST reactions. Our findings underline the need for a two-step approach in diagnosing latent TB infection in all BCG-vaccinated individuals: initial TST screening, followed by an IGRA to confirm TST positivity.

Publication types

  • Comparative Study

MeSH terms

  • Adjuvants, Immunologic / administration & dosage
  • Adolescent
  • Adult
  • BCG Vaccine / administration & dosage*
  • Cross-Sectional Studies
  • Female
  • Greece
  • Humans
  • Interferon-gamma*
  • Male
  • Military Personnel
  • Tuberculin Test / methods*
  • Tuberculosis / diagnosis*
  • Tuberculosis / immunology
  • Young Adult


  • Adjuvants, Immunologic
  • BCG Vaccine
  • Interferon-gamma