Rana El-Helbawy

Diagnostic value of the QuantiFERON-TB gold assay (T-SPOT.TB test) in patients with pulmonary tuberculosis after a full course of antituberculous therapy

Objectives The study aims to clarify the effectiveness of the T-SPOT.TB test as a method of evaluation of antituberculous (anti-TB) treatment. Background Among the various diagnostic tools of TB disease, the T-SPOT.TB test is the most advanced. It depends on the detection of interferon-g released from sensitized T cells when exposed to Mycobacterium tuberculosis antigens in vitro . Materials and methods The T-SPOT.TB test was carried out for two groups of individuals; the first group included 25 patients diagnosed previously by a positive culture of M. tuberculosis after a full course of anti-TB treatment. The second group included 10 healthy individuals. Results Twenty-one patients (84%) of the first group had a positive T-SPOT.TB test, whereas only four patients (16%) had a negative T-SPOT.TB test. Of the 23 patients with a negative result by culture and microscopy, 19 (82.6%) had a positive T-SPOT.TB test. Conclusion The T-SPOT.TB test is a weak test for use during treatment monitoring. As conversion of IGRA results might be later than smear conversion results of clinical specimens, we should not consider the IGRA test as a surrogate marker of a cure or a predictor of disease relapse.