Potential use of in vitro tests in the diagnosis of tuberculosis (literature review)

Abstract

The search for methods to improve early diagnosis of tuberculosis has been particularly active in the last two decades. Diagnostics of latent tuberculosis infection will increase the efficacy of anti-tuberculosis measures. Tuberculosis in HIV patients, which is increasingly common in the incident population, has specific clinical, immunological, and pathomorphological characteristics posing challenges to diagnosis confirmation. HIV-infected individuals have a 30-fold risk of tuberculosis compared with the general population. Diagnostic challenges are particularly high at the stage of severe immunodeficiency. In
the last two decades, IGRAs, which have a higher specificity versus tuberculin skin tests, have been increasingly used. We present a literature review of studies comparing the diagnostic efficacy of T-SPOT.TB and QuantiFERONTB Gold in-Tube assays in patients with suspected active tuberculosis. According to literature data, QuantiFERON assay more frequently yields false negative results in HIV patients with markedly decreased CD4+ cell counts. T-SPOT.TB sensitivity is essentially independent of age, whereby the sensitivity of QuantiFERON-TB reduces after the age of 30 years. T-SPOT.TB assay was not found to be affected by drug therapy. Based on this literature review, we assume that the use of T-SPOT.TB assay is most appropriate in the following cases: in patients taking drugs that inhibit gamma interferon production (glucocorticoids); in patients taking drugs that reduce leukocyte levels (NSAIDs: aspirin, paracetamol, Ketorol; also cytostatic agents etc.); in children under 5 years and in elderly subjects. T-SPOT.TB appears to be a promising test within the
assessment of HIV-infected patients.