Detection of latent tuberculosis by the tuberculin skin test and a whole-blood interferon-γ release assay, and the development of active tuberculosis in HIV-seropositive persons

Abstract

This study evaluated the QuantiFERON-TB Gold In-Tube (QFT-GIT; Cellestis, Carnegie, Australia) test and the tuberculin skin test (TST) for the detection of latent tuberculosis infection (LTBI) in HIV-infected adults. One hundred thirty-five HIV-seropositive persons and 135 controls underwent TST and QFT-GIT. HIV-infected patients who gave a positive result on either test were offered chemoprophylaxis. The prevalence of LTBI was 6.7% by TST and 9.6% by QFT-GIT (P = 0.3) in HIV-seropositive subjects, and 34.8% by TST and 21.5% by QFT-GIT (P = 0.02) among controls. TST reactivity declined sharply as CD4(+) cells fell (15.8%, 10.3%, and 0% for >500, 301-500 and ≤300 CD4(+) cells/mm(3), respectively; P = 0.002). A less pronounced fall occurred with QFT-GIT (15.8%, 13.8%, and 0% for >500, 301-500, and <100 CD4(+) cells/mm(3), respectively; P = 0.03). No cases of tuberculosis occurred during follow-up (0.26 per 100 person-years). Simultaneous testing with TST and QFT-GIT for targeting of chemoprophylaxis, early in the course of HIV infection, might minimize the risk of tuberculosis in these patients.