Interferon ?–Release Assays for Diagnosis of Latent Tuberculosis in Healthcare Workers in Low-Incidence Settings: Pros and Cons

[摘要] In well-resourced countries with a low incidence of tuberculosis (TB)16 (e.g., the US and Canada), a major focus of TB control efforts is the detection and treatment of latent TB infection (LTBI) to prevent reactivation to active TB disease. This approach is particularly relevant for healthcare workers (HCWs), and substantial resources are devoted to hospital TB-screening programs in low-incidence settings. Interferon γ–release assays (IGRAs), specifically the QuantiFERON-TB Gold In-Tube test (Cellestis) (QFT-GIT) and the T-SPOT. TB test (Oxford Immunotec), are used to detect and quantify the in vitro release of interferon γ from T cells stimulated by TB-specific antigens and can be used for LTBI diagnosis. Occupational-health and infection-control leaders in hospitals in low-incidence countries must decide whether to use IGRAs in their TB-screening programs in place of or in addition to the conventional tuberculin skin test (TST). This decision is complex, because IGRAs and the TST differ in terms of their costs and both their analytical and operational performance characteristics. Our understanding of the performance of these assays for baseline and serial testing in individuals with different risk factors for TB exposure and reactivation has been expanding rapidly. In this Q&A article, 5 experts in this field share their perspectives on the advantages and disadvantages of using IGRAs for screening HCWs for TB in settings of low TB incidence.What are the advantages and disadvantages of using IGRAs, compared to the TST, for baseline screening for LTBI in newly hired HCWs in low-incidence settings? Madhukar Pai: There is considerable evidence that both the TST and IGRAs are valid but imperfect tests for LTBI. While the TST has high specificity in persons who have not received the bacillus Calmette–Guérin (BCG) vaccine, its specificity is lower and variable in those who have received BCG postinfancy or via multiple vaccinations. In …

[学科分类] 过敏症与临床免疫学