[Which tuberculin skin test hyperreactive child should be treated with -our experience]

Since persons with latent tuberculosis infection (LTBI) represent a huge reservoir of potential tuberculosis (TB) disease, accurate diagnosis and treatment of LTBI is essential for TB control and eradication. The aim was to assess the diagnostic value of determination of interferon-gamma release assay in school children with hyperreactive tuberculin skin test (TST) reaction. A total of 120 BCG-vaccinated children were investigated due to a hyperreactive TST results. The QuantiFERON-TB Gold In-Tube test (QFT-GIT) was performed. Fifteen children (12.5%) had positive QFT-GIT and 105 (87.5%) children had negative QFT-GIT. There was no statistically significant difference in TST reaction (21.5 mm u QFT+ vs. 20.9 mm u QFT-group, p=0.458). The children with positive QFT-GIT had a statistically higher level of interferon-gamma (IFN-γ) than children with negative QFT-GIT. There were no statistically significant differences in concentrations of IFN-y either basic or upon stimulation with mitogen phytohemagglutinin. After isoniazid prophylaxis QFT-GIT remained positive in two children (p=0.019). In a difficult procedure for diagnosing LTBI in BCG-vaccinated children determination of IFN-γ could be the key factor in making decision whether to use preventive therapy or not.