Comparison of QuantiFERON-TB gold in-tube test with tuberculin skin test in children who had no contact with active tuberculosis case.

Introduction: In this study, we aimed to compare QuantiFERON-TB gold in-tube test (QFT-GIT) and tuberculin skin test (TST) as a diagnosis of latent tuberculosis infection in the children with Bacille Calmette-Guerin (BCG) vaccine.

Materials And Methods: We evaluated 81 children in the study who have positive TST result without a known history of tuberculosis contact from 2008 to 2011 prospectively. Patients were separated into groups according to their ages, the reason of TST application, number of BCG vaccination scars and diameter of TST induration. Posteroanterior, lateral chest radiographies and computerized tomography, if necessary, were performed.

Results: The study consists of 48 (59.3%) boys and 33 (40.7%) girls with a mean age of 94.8 ± 51.9 months (ranged from 6 to 193 months). Sixty nine (85.2%) children had one and 12 (14.8%) had two BCG vaccination scars. The TST induration diameters were 15-19 mm in 65 (80.2%) children and ≥ 20 mm in 16 (19.8%) children. QFT-GIT positivity was found in 12 (14.8%) of the evaluated patients. QFT-GIT positive patients were treated with triple anti-tuberculosis regime or isoniazid (INH). In three years period of study, there were no tuberculosis disease observed among the children who had not been treated with anti-tuberculosis drugs.

Conclusion: As a result of the study it is suggested to confirm positive TST results with tests based on interferon-gamma (IFN-γ) because it can reduce false positive diagnosis and treatment of latent tuberculosis infection, thus adverse reactions of drugs, in countries where BCG vaccination is routinely recommended especially for low risk children.