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: Asli Gorek Dilektasli, Elif Erdem, Elif Durukan, Füsun Öner Eyüboğlu
• Journal: Japanese journal of infectious diseases (Jpn J Infect Dis) Vol. 63 Issue 6 Pg. 433-6 (Nov 2010) ISSN: 1884-2836 [Electronic] Japan
• PMID: 21099095 (Publication Type: Comparative Study, Evaluation Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• BCG Vaccine
• Culture Media
• Interferon-gamma

Topics

• Adult
• BCG Vaccine (administration & dosage, immunology)
• Culture Media
• Humans
• Immunoassay (methods)
• Incidence
• Interferon-gamma (biosynthesis)
• Latent Tuberculosis (diagnosis, microbiology)
• Middle Aged
• Mycobacterium tuberculosis (immunology, isolation & purification)
• Predictive Value of Tests
• Sensitivity and Specificity
• T-Lymphocytes (immunology)
• Tuberculin Test
• Tuberculosis, Pulmonary (diagnosis, epidemiology, microbiology, prevention & control)
• Turkey (epidemiology)
• Young Adult