The complexity of diagnosing latent tuberculosis infection in older adults in long-term care facilities

Natasha S. Hochberg, Sergey Rekhtman, Julianne Burns, Lisa Ganley-Leal, Sina Helbig, Nathaniel S. Watts, Gary H. Brandeis, Jerrold J. Ellner, C. Robert Horsburgh

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Objectives: 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.

Original languageEnglish (US)
Pages (from-to)37-43
Number of pages7
JournalInternational Journal of Infectious Diseases
Volume44
DOIs
StatePublished - Mar 1 2016
Externally publishedYes

Keywords

  • Interferon-gamma release assays
  • Latent tuberculosis
  • Long-term care facility
  • Nursing homes

ASJC Scopus subject areas

  • Microbiology (medical)
  • Infectious Diseases

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