Tests for diagnosing TB infection
| TST | New skin tests | IGRAs and in vitro tests | New in vitro tests | |
| Examples | Diaskin test, EC-skin test and c-Tb | QuantiFERON-TB Gold Plus and T-SPOT.TB Standard E TB-Feron, AdvanSure TB-IGRA ELISA, LIOFeron TB/LTBI, IP-10 ELISA | QIAreach QuantiFERON-TB, the ichroma IGRA-TB, STANDARD F TB-Feron FIA, Erythra TB-test, IP-10 IGRA LF VIDAS TB-IGRA, AdvanSure I3 TB-IGRA, LIAISON QuantiFERON-TB Gold Plus, GBTsol Latent TB Test Kit | |
| Characteristics | Intradermal administration of PPD in the forearm Cold chain requirement for PPD Induration reading within 72 h Trained staff for administration and reading the skin induration | Intradermal administration of ESAT-6/CFP-10 antigens in the forearm Cold chain requirement for ESAT-6/CFP-10 Induration reading within 72 h Trained staff for administration and reading the skin induration | In vitro tests with internal controls Detection of IFN-γ or other markers in blood or PBMCs using ELISA Need for fresh samples Incubation time of 16–24 h Need for efficient sample transport system Need for different blood collection tubes depending on the altitude Need for laboratory infrastructure Assay time: 20 min for IP-10 ELISA; 1.5–4 h for QuantiFERON-TB Gold Plus, T-SPOT.TB, Standard E TB-Feron, AdvanSure TB-IGRA ELISA, LIOFeron TB/LTBI | In vitro tests with internal controls Detection of IFN-γ or other biomarkers in the blood or isolated T-cells using LFA or chemiluminescence or ELFA systems Need for fresh samples Incubation time of 0#–24 h Need for efficient sample transport system Need for different blood collection tubes depending on the altitude Need for laboratory infrastructure for some assays¶ Assay time: 15–20 min for QIAreach QuantiFERON-TB, STANDARD F TB-Feron FIA, ichroma IGRA-TB, AdvanSure I3 TB-IGRA, Erythra TB test; 46 min to 17 h+ for LIAISON QuantiFERON-TB Gold Plus, GBTsol Latent TB Test Kit, GBTsol Latent TB Test Kit, IP-10 IGRA LF and VIDAS TB-IGRA |
| Disadvantages | False positive results in BCG-vaccinated individuals False negative results in immunocompromised hosts Inaccuracy/bias in performing the test and in reading it Second visit needed | False negative results in immunocompromised hosts Inaccuracy/bias in performing the test and in reading it | False negative results in immunocompromised Errors in the pre-analytical phase Misinterpretation of the assays Expensive | Limited data We expect: Errors in the pre-analytical phase Misinterpretation of the assays Expensive |
| Advantages | Useful for large screening settings Cost-effective No laboratory infrastructure required | Useful for large screening settings Cost-effective No laboratory infrastructure required | Higher specificity for TB infection compared with TST No booster effect compared with TST No need for a second visit compared with TST Faster turn-around time compared with TST | Higher specificity for TB infection compared with TST No booster effect No need for a second visit compared with TST Lower turn-around time compared with IGRAs Very likely: faster§ and/or less handlingƒ compared with IGRAs |
Assay time: time from post-incubation and result delivery. Incubation time: time of stimulation. BCG: bacille Calmette–Guérin; ELFA: enzyme-linked fluorescence assay; ELISA: enzyme-linked immunosorbent assay; LFA: lateral flow assay; PBMC: peripheral blood mononuclear cells. #: incubation time not required for Erythra TB-test; ¶: VIDAS TB-IGRA, AdvanSure I3 TB-IGRA, LIAISON QuantiFERON-TB Gold Plus; +: VIDAS TB-IGRA assay time is reported to be 17 h and includes incubation, post-incubation and result score; §: applies to QIAreach QuantiFERON-TB, the ichroma IGRA-TB, STANDARD F TB-Feron FIA, Erythra TB-test, AdvanSure I3 TB-IGRA; ƒ: applies to VIDAS TB-IGRA, LIAISON QuantiFERON- TB Gold Plus.