Discrepancy between the results of immunological tests in children with tuberculosis infection

<b>Objective:</b> to identify the results of immunological tests in children with tuberculosis infection. <b>Material and methods:</b> 73 patients with positive results of the skin test with tuberculous recombinant allergen (TRA) from 1 to 17 years old were examined at Saint-Petersburg TB dispensaries № 2, 5, 14, 16 during 2015-2018. <b>Diagnostic Complex Included:</b> clinical, immunological (tuberculin skin test (TST), T-SPOT.TB (T-SPOT), bacteriological and X-rays methods (computed tomography). All patients were divided in 2 groups: I (34) - with positive results of T-SPOT, II (39) - with negative results of T-SPOT. <b>Results:</b> The age of the patients in the groups was as follows: I group – 2 (5.9%) 1-6 y.o., 27 (79.4%, χ2=12.47, p=0,0004) 7-14 y.o., 5 (14.7%) adolescents 15-17 y.o.; II group – 15 (38.4%, χ2=10.79, p=0,0001) 1-6 y.o., 15 (38.5%) 7-14 y.o., 9 (23.1%) adolescents. There are statistically significant differences in results of TRA between group: 13.97± 1.89 mm (I) vs. 10.08±1.10 mm (II). 18 children in group I were diagnosed with signs of tuberculosis by computed tomography, in II group only one patient had a single calcinate in the lung (χ2=23.94, p &lt;0,0001). <b>Conclusions:</b> The discrepancy between the results of immunological tests was significantly more frequently observed in young children, with a low TRA results and the absence signs of tuberculosis in the lungs and intrathoracic lymph nodes.