Comparison of mantoux skin test with three generations of a whole blood IFN-gamma assay for tuberculosis infection.
METHODS
A rural town in South Africa.


OBJECTIVE
To compare the performance of Quanti-FERON assays with the tuberculin skin test (TST) for identifying latent tuberculosis infection (LTBI) in a high TB burden community.


METHODS
In a cross-sectional study in healthy adults, we applied the TST and took blood for the three generations of QuantiFERON assays.


RESULTS
Of 358 participants whose results were analysed, 291 (81%) had a TST result of > or = 10 mm induration, and 187 (52%) > or = 15 mm. QuantiFERON-TB was positive in 215 (60%), QuantiFERON-TB Gold in 137 (38%), and QuantiFERON-TB Gold (In-Tube method) in 201 (56%). There was poor agreement between TST and QuantiFERON tests, and between the different generations of QuantiFERON tests (kappa = 0.12-0.50). Of the subset with TST indurations > or = 15 mm, 30-56% had negative QuantiFERON tests. However, positive Quanti-FERON tests were associated with males, who have a higher incidence of TB in this area.


CONCLUSIONS
We showed poor agreement between TST and the different QuantiFERON tests in diagnosing LTBI. The surprising discordance between the Quanti-FERON TB Gold and QuantiFERON TB Gold (In-Tube method) tests needs to be investigated further.
South African Tuberculosis Vaccine Initiative, Institute of Infectious Disease and Molecular Medicine, School of Child and Adolescent Health, University of Cape Town, Cape Town, South Africa. hassan@rmh.uct.ac.za
H
H
Mahomed
E J
EJ
Hughes
T
T
Hawkridge
D
D
Minnies
E
E
Simon
F
F
Little
W A
WA
Hanekom
L
L
Geiter
G D
GD
Hussey
D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000097:blood; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D015994:Incidence; D007371:Interferon-gamma / Q000097:blood*; D008297:Male; D012307:Risk Factors; D012424:Rural Population; D013019:South Africa / Q000453:epidemiology; D014374:Tuberculin Test; D014376:Tuberculosis / Q000097:blood* / Q000175:diagnosis* / Q000453:epidemiology
D015415:Biomarkers; D007371:Interferon-gamma