Using IFN-gamma release assay to confirm tuberculin skin test improves the screening of latent tuberculosis infection in Italian healthcare workers

Abstract

BackgroundHealthcare workers (HCWs) represent a tuberculosis (TB) risk group for a wide range of tasks in healthcare, even in countries with low TB incidence, like Italy. Latent Tuberculosis Infection (LTBI) screening programs are an important tool for TB prevention in these setting.MethodsA retrospective study under a LTBI screening program among HCWs at the Siena University Hospital (Italy), was conducted between September 2011 and July 2015. Tuberculin Skin Test (TST) was used as a first level examination; all TST-positive cases were tested with QuantiFERON-TB Gold In-Tube (QFT-GIT) test, together with a group of TST-negative subjects.ResultsAmong the 2136 HCWs screened, 144 (6.7 %) were TST-positive and therefore tested with QFT-GIT, confirming a positive result in 36 cases (25 %). Agreement between two tests was poor (k = 0.092; 95 %, Confidence Interval [CI]- 0.048–0.136, p = 0.002). Among TST-positive cases, discordant results occurred more frequently in BCG vaccinated than unvaccinated HCWs (86.3 %, p < 0.001). The probability of a QFT-GIT-positive result increased according to the TST diameter (p = 0.001). No putative risk factor was associated with LTBI occurrence.ConclusionsThe use of QFT-GIT test as a second step in TST-positive cases offers an appropriate tool for LTBI detection, especially among BCG-vaccinated HCWs.

Prevalence of latent tuberculosis infection among coal workers’ pneumoconiosis patients in China: a cross-sectional study

“…To date, besides a study that investigated the prevalence of LTBI among aged underground hard coal miners using IGRAs in Germany and reported positive rates of 46.6% (QFT) and 61.0% (T-SPOT) [ 11 ], no studies have reported the prevalence of LTBI among CWP patients in the rest of the world. As for occupational studies, a few reports employed the IGRA in healthcare workers and detected positive rates of 9.9% (QFT) in Japan [ 14 ], 10.6% (QFT) in Malaysia [ 15 ], 25% (QFT) in Italy [ 16 ], 40.8% (QFT) in Russia [ 17 ], 46% (QFT) in Georgia [ 18 ], 76.7% (QFT) and 65.7% (A.TB, a Mycobacterium tuberculosis -specific cell-mediated immune response detection kit) in China [ 8 ], and 46.0% (QFT) among village doctors in China [ 19 ]. The prevalence of LTBI in healthcare workers therefore varied greatly between countries, with a much higher LTBI rate in China than in any of the other countries.…”

High prevalence of latent tuberculosis in hematopoietic stem cell transplant recipients: A First Report

“…In addition, TST was performed by trained staffs following standard procedures. Intradermal injection of 2 IU (0.1 mL) of standardized purified protein derivative solution (TUBERTEST®, Sanofi Pasteur MSD, France) was performed into the volar surface of the forearm at the same time with blood sampling for IGRA test 19 . The reaction to TST was measured after 48‐72 hours from the injection by personnel trained to read TST results, while self‐reporting of results was not permissible.…”

Screening of a ScFv Antibody With High Affinity for Application in Human IFN-γ Immunoassay

“…IFN-γ is a small size of cytokine containing 146 amino acids in the maturated peptide, and it is also the sole member of the type 2 interferon family ( Wu et al, 2017 ). Recently, IFN-γ detection was regarded as an important biomarker and employed to diagnose latent tuberculosis in clinic ( Liu et al, 2012 ; Chegou et al, 2013 ; Olivieri et al, 2016 ). Some published papers have demonstrated that IFN-γ is required to prime macrophages in order to become fully activated and induce an efficient type I response in African trypanosome infections ( Magez et al, 2002 ; Mansfield and Paulnock, 2005 ; Cnops et al, 2015 ).…”