In this study, M. tuberculosis F15/LAM4/KZN strain phage secretome library was screened against immobilized polyclonal sera from active TB patients (n = 20), TST positive individuals (n = 15) and M. tuberculosis uninfected individuals (n = 20) to select and identify proteins recognized by patients' antibodies.
Comparative results of both tests in 408 patients with tuberculosis: at cut-off ≥ 5 mm, both tests has similar sensitivity: Diaskintest 98.3% (95% CI 97.0-99.6%), TST 98.0% (95% CI 96.7-99.4%), at cut-off ≥10 mm, the sensitivity decreases for both tests: Diaskintest 90.0% (95% CI 87.0-93.0%), TST 88.7% (95% CI 85.6-91.9%), but at cut-off ≥ 15 mm, the decrease in sensitivity is statistically significant: for Diaskintest 61.5% (95% CI 56.7-66.3%), and for TST 46.3% (95% CI 41.4-51.3%), p <0.0001.
Patients were 6.95 times more likely to have intraocular tuberculosis if TST alone was positive (p < 0.001) versus 2.19 times more likely if Quantiferon alone was positive (p = 0.04).
In contrast, the NRAMP1 3'UTR variants were associated with susceptibility to M. tuberculosis infection, as seen in the comparisons between TST+ and TST- controls, and also with progression to TB disease, as shown in the comparisons between TB patients and TST+ controls.