Discordant tuberculin skin and interferon-gamma tests during contact investigations: a dilemma for tuberculosis controllers.
Current recommendations conflict over the appropriate use of interferon-gamma whole blood assays to screen for tuberculosis (TB) infection in contact investigations. We report here on a worksite TB contact investigation in which tuberculin skin test (TST) and QuantiFERON-TB Gold (QFT-G) were both used to identify infection among 61 co-workers. Of the 27 (44%) who had a TST > or =15 mm, 11 (41%) had negative QFT-G, raising concerns that QFT-G may not be sufficiently sensitive when used alone in contact investigations. The questionable performance of QFT-G in this setting is not unexpected, as the negative predictive value of a test decreases with increasing prevalence.
O'Neal
S
S
Oregon Health and Sciences University, Portland, Oregon, USA. oneals@ohsu.edu
Hedberg
K
K
Markum
A
A
Schafer
S
S
D000328:Adult; D015415:Biomarkers / Q000097:blood; D018562:Disease Transmission, Infectious / Q000517:prevention & control* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D015994:Incidence; D017053:Infection Control / Q000379:methods*; D007371:Interferon-gamma / Q000097:blood*; D008297:Male; D009922:Oregon / Q000453:epidemiology; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014374:Tuberculin Test / Q000379:methods*; D014376:Tuberculosis / Q000175:diagnosis* / Q000453:epidemiology / Q000635:transmission
D015415:Biomarkers; D007371:Interferon-gamma