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.
Mahomed
H
H
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
Hughes
E J
EJ
Hawkridge
T
T
Minnies
D
D
Simon
E
E
Little
F
F
Hanekom
W A
WA
Geiter
L
L
Hussey
G D
GD
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