title: Comparison of a new ESAT-6/CFP-10 peptide-based gamma interferon assay and a tuberculin skin test for tuberculosis screening in a moderate-risk population.
abstract: Screening for latent tuberculosis infection (LTBI) with Mantoux tuberculin skin test (TST) has many limitations, including false-positive results due to exposure to Mycobacterium other than tuberculosis (TB) and BCG vaccination. A total of 474 adult inmates in a county jail were screened for LTBI using TST and a new ESAT-6/CFP-10 peptide-based whole-blood gamma interferon (IFN-gamma) assay. LTBI prevalence was 9.0 and 5.4% as determined by TST and IFN-gamma assay, respectively. Overall, agreement between test results was 90% (kappa = 0.25). Positive TST results were significantly associated with increased age (odds ratio [OR], 1.04; 95% confidence interval [CI], 1.01 to 1.08), African-American ethnicity (OR, 4.97; 95% CI, 1.58 to 15.68), foreign birth (OR, 20.20; 95% CI, 4.21 to 97.02) and prior incarceration (OR, 6.19; 95% CI, 1.48 to 25.95). Positive IFN-gamma assay results were significantly associated with African-American ethnicity (OR, 5.58; 95% CI, 1.16 to 26.74). Factors associated with statistically significant discordance between TST and IFN-gamma assay results were African-American ethnicity (OR, 0.29; 95% CI, 0.11 to 0.77), foreign birth (OR, 0.23; 95% CI, 0.07-0.80), and prior incarceration (OR, 0.06; 95% CI, 0.01-0.50). Among subjects born in the United States, African-American ethnicity was the only variable significantly associated with positive test results for both TST (OR, 4.26; 95% CI, 1.38 to 13.16) and IFN-gamma assay (OR, 5.74; 95% CI, 1.19 to 27.75) and remained associated with statistically significant discordance between TST and IFN-gamma assay results. The reactivity of the new IFN-gamma assay is unaffected by prior BCG vaccination or serial TSTs but may be diminished in African-Americans. Future longitudinal studies are needed to assess the sensitivity and specificity of this new assay in detecting LTBI.
authors.affiliation: Department of Family and Community Medicine, MSB-G.150, The University of Texas Health Science Center, Houston, TX 77002, USA. esmaeil.porsa@uth.tmc.edu
authors.forename: Emaeil
authors.initials: E
authors.lastname: Porsa
authors.forename: Lee
authors.initials: L
authors.lastname: Cheng
authors.forename: Michael M
authors.initials: MM
authors.lastname: Seale
authors.forename: George L
authors.initials: GL
authors.lastname: Delclos
authors.forename: Xin
authors.initials: X
authors.lastname: Ma
authors.forename: Robert
authors.initials: R
authors.lastname: Reich
authors.forename: James M
authors.initials: JM
authors.lastname: Musser
authors.forename: Edward A
authors.initials: EA
authors.lastname: Graviss
mesh_terms: D000293:Adolescent; D000328:Adult; D001741:Black or African American / Q000208:ethnology; D000942:Antigens, Bacterial / Q000276:immunology*; D001426:Bacterial Proteins / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007159:Immunologic Tests; D007371:Interferon-gamma / Q000097:blood* / Q000276:immunology*; D008297:Male; D008403:Mass Screening / Q000379:methods; D015999:Multivariate Analysis; D016017:Odds Ratio; D010455:Peptides / Q000378:metabolism; D011237:Predictive Value of Tests; D015995:Prevalence; D011329:Prisoners; D012307:Risk Factors; D013781:Texas / Q000453:epidemiology; D014374:Tuberculin Test; D014376:Tuberculosis / Q000175:diagnosis* / Q000453:epidemiology / Q000276:immunology
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C117940:CFP-10 protein, Mycobacterium tuberculosis; C093276:ESAT-6 protein, Mycobacterium tuberculosis; D010455:Peptides; D007371:Interferon-gamma