title: The complexity of diagnosing latent tuberculosis infection in older adults in long-term care facilities.
abstract: OBJECTIVE
  In the USA, tuberculosis disease rates are highest in older adults. Diagnostic testing for latent tuberculosis infection (LTBI) has not been evaluated carefully in this group. The aim of this study was to define the relationship between tuberculin skin test (TST) results, T-SPOT.TB results, and T-cell responses to Mycobacterium tuberculosis antigens.
  
  
  METHODS
  Long-term care facility residents with known prior TST results (positive or negative) were retested with TSTs and T-SPOT.TB. Prior exposure to M. tuberculosis was assessed by quantifying T-cell activation to mycobacterial antigens in vitro.
  
  
  RESULTS
  The median age of the 37 participants was 77 years (range 57-98 years). Among 18 participants with a prior positive TST, three (16.7%) had a negative TST when retested (TST reversion); two had a negative T-SPOT.TB. Of the 15 who were historically and currently TST-positive, four (26.7%) had a negative T-SPOT.TB and one (6.7%) had a borderline result. Percentages of CD4+ T-cells responding to mycobacterial antigens were higher in participants with positive TST and T-SPOT.TB (18.2%) compared to those with a positive TST but negative T-SPOT.TB (6.4%, p=0.16) and negative TST and T-SPOT.TB (5.9%, p<0.001).
  
  
  CONCLUSIONS
  LTBI testing in older adults is complicated by TST reversion and TST-positive/T-SPOT.TB-negative discordance, which may reflect clearance of infection or waning immunity.
authors.affiliation: Department of Medicine, Section of Infectious Diseases, Boston University School of Medicine, 801 Massachusetts Avenue, Rm 2012 Boston, MA 02118, USA; Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts, USA. Electronic address: nhoch@bu.edu.
authors.forename: Natasha S
authors.initials: NS
authors.lastname: Hochberg
authors.affiliation: Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts, USA.
authors.forename: Sergey
authors.initials: S
authors.lastname: Rekhtman
authors.affiliation: Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts, USA.
authors.forename: Julianne
authors.initials: J
authors.lastname: Burns
authors.affiliation: Department of Medicine, Section of Infectious Diseases, Boston University School of Medicine, 801 Massachusetts Avenue, Rm 2012 Boston, MA 02118, USA.
authors.forename: Lisa
authors.initials: L
authors.lastname: Ganley-Leal
authors.affiliation: Department of Medicine, Section of Infectious Diseases, Boston University School of Medicine, 801 Massachusetts Avenue, Rm 2012 Boston, MA 02118, USA.
authors.forename: Sina
authors.initials: S
authors.lastname: Helbig
authors.affiliation: Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts, USA.
authors.forename: Nathaniel S
authors.initials: NS
authors.lastname: Watts
authors.affiliation: Department of Medicine, Section of Geriatric Medicine, Boston University School of Medicine, Boston, Massachusetts, USA.
authors.forename: Gary H
authors.initials: GH
authors.lastname: Brandeis
authors.affiliation: Department of Medicine, Section of Infectious Diseases, Boston University School of Medicine, 801 Massachusetts Avenue, Rm 2012 Boston, MA 02118, USA.
authors.forename: Jerrold J
authors.initials: JJ
authors.lastname: Ellner
authors.affiliation: Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts, USA.
authors.forename: C Robert
authors.initials: CR
authors.lastname: Horsburgh
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D055985:Latent Tuberculosis / Q000175:diagnosis*; D008134:Long-Term Care; D008213:Lymphocyte Activation; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000276:immunology; D012680:Sensitivity and Specificity; D013601:T-Lymphocytes / Q000276:immunology*; D014374:Tuberculin Test / Q000379:methods
keywords: Interferon-gamma release assays; Latent tuberculosis; Long-term care facility; Nursing homes