VALIDITY OF A NEGATIVE SKIN TEST RESULT WITH RECOMBINANT TUBERCULOSIS ALLERGEN IN ORDER TO EXCLUDE THE ACTIVE TUBERCULOSIS IN CHILDREN

Abstract

Detection of tuberculosis (TB) infection and prophylactic anti-tuberculosis treatment in order to prevent cases of the disease is a current priority in phthisiatry. The effective screening of the TB infection requires the availability of effective tests with high sensitivity and specificity. The purpose of the study was to assess the concordance of a negative result of a recombinant tuberculosis allergen (RTA) test and the absence of specific changes on multi-slice computed tomography (MSCT) of the chest organs in children aged 3 to 14 years old who are not at risk for the TB development in territories with a low incidence of TB. Materials and methods of the study: a multicenter cohort retrospective study of children 3 to 14 years old who do not belong to risk groups for the TB development, without clinical symptoms of any disease and with a negative RTA test result. An analysis of the data of the objective examination of the child, of the general blood test study, of the results of previous immunodiagnostics, and of the results of MSCT of the chest organs (the presence of changes of any nature in the lungs and intrathoracic lymph nodes) was performed. Results: 43 children were included in the study, 65% (28) males. The average age of children was 7.0 [6.0; 11.0] years. Two age groups of children were studied - 3 to 7 and 8 to 14 years old. In the group of children aged 3 to 7 years old, only 68% had information about a previous tuberculinogram, on the basis of which it was possible to judge the presence of a possible active TB infection. In 14 children of this age group, pronounced reactions to tuberculin were noted, which was an indication for the Mantoux test with 2 tuberculin units (2TU) for an in-depth examination and consultation with a phthisiatrician (increase in tuberculin sensitivity). The concordance of the negative result of the RTA test and the negative result of the Mantoux test with 2TU was 50% - the value is random, while in all children according to MSCT of the chest organs, there were no specific changes. The concordance of a negative result of the RTA test and the absence of specific changes on MSCT of the chest organs was 100%. Conclusion: in children who do not belong to the risk group for the TB development, a negative result of the RTA test was accompanied by the absence of changes in the MSCT of the chest organs (100% concordance). The tuberculin diagnostics using the Mantoux test with 2TU has significant limitations for detection of the TB infection in children under 7 years of age. For children aged 3 to 7 years old who have been diagnosed with mycobacterium TB infection and do not need to be re-introduced with BCG vaccine, it is reasonable to screen for TB using the RTA test.