Modern immunodiagnostics of tuberculosis infection in adults

Despite the steady decline in the main epidemiologically significant indicators of tuberculosis in Russia, the problem remains of choosing an affordable and informative diagnostic test for the timely detection of latent tuberculosis infection (LTI). The aim of this study was to evaluate the compatibility of various methods of immunological diagnosis in adult patients with LTI with a high (LTI-HR) and low (LTI-LR) risk of developing tuberculosis, as well as in patients with established tuberculosis of the respiratory system. Methods. A cross-sectional open single-center study was conducted, which included 100 adult patients. The first group included 50 conditionally healthy individuals with LTI-LR. The second group of patients consisted of 25 people with LTI-HR. The third group of patients included 25 patients with tuberculosis of the respiratory system (TRS). All participants were examined once using six immunological diagnostic tests: Mantoux test with 2 units PPD-L, Diaskintest, T-SPOT®.TB, QuantiFERON®-TB Gold Plus, Standard E TB-Feron IGRA and IGRA-TB. The end point of the study was the overall percentage consistency of the results, that is, the ability of the tests to correctly predict the condition assumed by the combination of clinical signs. Results. The proportion of “correct results” (positive in the TRS and LTI-HR group and negative in the LTI-LR group) was 83% for the IGRA-TB test, 80% for the Diaskintest, 80% for the QuantiFERON®-TB Gold Plus test, 78% for the Standard E TB-Feron IGRA test, 67% for the T-SPOT®.TB test ( p > 0.05). Only the Mantoux test with 2 units PPD-L showed significantly lower “accuracy” in our study (53%; p < 0.05). Conclusion. The new Russian test IGRA-TB is not inferior to its foreign counterparts and can be recommended in practical healthcare as a diagnosis of latent tuberculosis infection in adults. It seems fundamentally important to continue studying the informative value of tests in adult patients in real clinical practice without applying strict selection criteria. The immunological features of the patients, which determine the different sensitivity of the tests, need to be further studied.