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


METHODS
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).


CONCLUSIONS
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.
Katsenos
S
S
Department of Pneumonology, University Hospital of Ioannina, Ioannina, Greece.
Nikolopoulou
M
M
Konstantinidis
A K
AK
Gartzonika
C
C
Gogali
A
A
Margelis
I
I
Tatsioni
A
A
Mavridis
A
A
Constantopoulos
S H
SH
Daskalopoulos
G
G
D000276:Adjuvants, Immunologic / Q000008:administration & dosage; D000293:Adolescent; D000328:Adult; D001500:BCG Vaccine / Q000008:administration & dosage*; D003430:Cross-Sectional Studies; D005260:Female; D006115:Greece; D006801:Humans; D007371:Interferon-gamma; D008297:Male; D008889:Military Personnel; D014374:Tuberculin Test / Q000379:methods*; D014376:Tuberculosis / Q000175:diagnosis* / Q000276:immunology; D055815:Young Adult
D000276:Adjuvants, Immunologic; D001500:BCG Vaccine; D007371:Interferon-gamma