Comparison of QuantiFERON-TB Gold and Tuberculin Skin Testing
| QuantiFERON-TB Gold | TST | |
|---|---|---|
| How is the test performed? | Laboratory measurement of interferon-gamma in whole blood | Intradermal injection of purified protein derivative and measurement of resulting induration |
| What does the test measure? | In vitro release of interferon gamma after exposure to specific M. tuberculosis antigens | In vivo type intradermal hypersensitivity after injection of a mixture of mycobacterial antigens (not only M. tuberculosis) |
| Ability to detect tuberculous infection | Yes | Yes |
| Ability to distinguish latent and active tuberculosis | No | No |
| False positive results | Yes, but less frequently than with the TST. False-positive results may occur with exposure to selected nontubercular mycobacteria, but not after BCG vaccination. | Yes. False-positive results may occur after exposure to nontubercular mycobacteria or after BCG vaccination. |
| False negative results | Possible among immunosuppressed individuals | Possible among immunosuppressed individuals |
| Effect of BCG vaccination | None | May give a false-positive result after BCG vaccination |
| Need for patient to return for second visit | No | Yes, for reading of the skin reaction |
| Required infrastructure | Yes. Special equipment required in the laboratory | No special infrastructure required. Easy to perform even in unsophisticated facilities |
| Subjectivity in reporting results | No | Yes, it may vary depending on training of individual |
| Cost | More expensive | Less expensive |
| Time to obtain result | At least 24 hours, but longer if run in batches | At least 48 hours |
| Boosting an anamnestic response with successive tests | No | Yes |
TST, tuberculin skin test; BCG, Bacillus Calmette-Guérin.