title: Is the T-cell-based interferon-gamma releasing assay feasible for diagnosis of latent tuberculosis infection in an intermediate tuberculosis-burden country?
abstract: The diagnosis of active and latent tuberculosis infection (LTBI) remains a challenge, especially in light of the fact that the tuberculin skin test (TST), which has been used to diagnose LTBI for over a century, has many well-known drawbacks. This study aimed to compare the diagnostic performance of the T-cell-based interferon-gamma releasing assay (IGRA) T-SPOT.TB with the TST for the diagnosis of LTBI in an intermediate tuberculosis (TB)-burden country with high BCG coverage. For this purpose, a total of 91 participants, including culture-confirmed TB patients, healthy contacts known to have been exposed to Mycobacterium tuberculosis, and healthy volunteers, selected from a BCG-vaccinated population were recruited. The sensitivities of the T-SPOT.TB and TST were 79.3 and 25.8%, and the specificities were 75.9 and 56.7%, respectively. The negative- and positive-predictive values for T-SPOT.TB and TST were 78.6 and 76.7% and 42.5 and 38.1%, respectively. The diagnostic performance of the TST in LTBI diagnosis is therefore severely diminished in BCG-vaccinated populations, with the sensitivity and specificity of the T-SPOT.TB assay being markedly higher. IGRAs have been reported to have higher diagnostic sensitivity and specificity in low TB-incidence settings than those seen here. Further larger scale studies in high and intermediate TB-incidence settings are therefore warranted.
authors.affiliation: Department of Pulmonary Diseases, Baskent University School of Medicine, Ankara, Turkey. asligorekd@gmail.com
authors.forename: Asli Gorek
authors.initials: AG
authors.lastname: Dilektasli
authors.forename: Elif
authors.initials: E
authors.lastname: Erdem
authors.forename: Elif
authors.initials: E
authors.lastname: Durukan
authors.forename: Füsun Öner
authors.initials: FÖ
authors.lastname: Eyüboğlu
mesh_terms: D000328:Adult; D001500:BCG Vaccine / Q000008:administration & dosage / Q000276:immunology; D003470:Culture Media; D006801:Humans; D007118:Immunoassay / Q000379:methods; D015994:Incidence; D007371:Interferon-gamma / Q000096:biosynthesis*; D055985:Latent Tuberculosis / Q000175:diagnosis* / Q000382:microbiology; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000276:immunology / Q000302:isolation & purification; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D013601:T-Lymphocytes / Q000276:immunology*; D014374:Tuberculin Test; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis / Q000453:epidemiology* / Q000382:microbiology / Q000517:prevention & control; D014421:Turkey / Q000453:epidemiology; D055815:Young Adult
chemical_list: D001500:BCG Vaccine; D003470:Culture Media; D007371:Interferon-gamma