Sensitivity and specificity of new skin test with recombinant protein CFP10-ESAT6 in patients with tuberculosis and individuals with non- tuberculosis diseases

Background: A new preparation for skin testing contains recombinant proteins CFP10-ESAT6 (DIASKINTEST or DST) being absent in all M. bovis BCG substrains and most environmental mycobacteria. The aim: To determine sensitivity and specificity of DST in adults with pulmonary, extrapulmonary tuberculosis (TB), non-tuberculosis diseases. Method: 609 patients with active lung TB and 559 - with non-active; 38 with active extrapulmonary TB and 29 with non-active; 220 patients with non-tuberculosis lung diseases,133 with non-tuberculosis extrapulmonary diseases; 29 patients with mycobacterioses received skin test: DST (0.2 mkg/0.1 ml). Result. 85,1% (423/497) patients with active lung TB, who had received treatment for 1- 30 days, 54.5% (61/112) patients, who had received treatment for 100-120 days, 15,3% (91/595) patients, who completed treatment were DST-positive. 89,4% (34/38) with extrapulmonary TB were DST- positive. 27out 29 patients with non-active extrapulmonary TB were DST- negative. 96,9% (129/133) with extrapulmonary non-tuberculosis diseases were DST-negative. 95,9% (211/220) patients with non-tuberculosis pulmonary diseases were DST- negative. Among 8 patients with mycobacterioses caused by M. avium 6 were DST negative; 14 caused by M. kansasii 8 were DST-positive,7 caused by M. xenopi, M. fortuitum, M. chelonae were DST- negative. This was attributed to the fact that M.avium, M. xenopi, M. Fortuitum, M. chelonae don’t secrete proteins ESAT-6 and CFP-10, which are part of DST, while M. kansasii secreted the above proteins. Conclusion: DST could be used for TB detection, evaluation of TB activity and treatment effectiveness.