Early diagnosis of subclinical multidrug-resistant tuberculosis

Ann Intern Med. 2004 May 4;140(9):709-13. doi: 10.7326/0003-4819-140-9-200405040-00010.


Background: Tuberculosis control hinges on prompt diagnosis of active cases and screening of contacts by tuberculin skin testing. Rapid blood tests for Mycobacterium tuberculosis infection are a new alternative to the tuberculin skin test, but whether they improve clinical outcomes is unknown.

Objective: To describe how a novel T-cell-based test for M. tuberculosis infection helped diagnose tuberculosis in an asymptomatic, immunosuppressed adult with a negative result on a tuberculin skin test.

Design: Case report.

Setting: Household contact.

Patients: Asymptomatic man receiving maintenance azathioprine therapy for Crohn disease whose wife had multidrug-resistant pulmonary tuberculosis.

Measurements: Enzyme-linked immunospot (ELISPOT) assay, computed tomography, and bronchoalveolar lavage cultures.

Results: The man had a negative tuberculin skin test result and a positive ELISPOT assay result. High-resolution computed tomography of the chest showed consolidation with early cavitation. Bronchoalveolar lavage and culture confirmed multidrug-resistant tuberculosis.

Limitations: This single case report is a proof of concept and is not a formal evaluation of clinical utility.

Conclusions: A positive ELISPOT assay result helped diagnose subclinical active tuberculosis in an immunosuppressed patient with a false-negative tuberculin skin test result. Large prospective studies that compare benefits and costs of this alternative to tuberculin skin testing are needed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antigens, Bacterial / analysis
  • Azathioprine / therapeutic use
  • Bronchoalveolar Lavage
  • Crohn Disease / drug therapy
  • Early Diagnosis
  • Female
  • Humans
  • Immunocompromised Host*
  • Immunoenzyme Techniques*
  • Immunosuppressive Agents / therapeutic use
  • Mycobacterium tuberculosis / immunology
  • T-Lymphocytes / immunology
  • Tomography, X-Ray Computed
  • Tuberculosis, Multidrug-Resistant / diagnosis*
  • Tuberculosis, Multidrug-Resistant / immunology*


  • Antigens, Bacterial
  • Immunosuppressive Agents
  • Azathioprine